DOI: 10.3897/aiep.56.209443

Authors: Siwar Agrebi, Rym Ennouri, Faten Alayet, Amor Hedfi, Ibtissem Louiz, Manel Ben Ali, Ezzeddine Mahmoudi, Sami Mili

Abstract: The white anglerfish, Lophius piscatorius Linnaeus, 1758, is a demersal species of great ecological and commercial importance in Tunisian waters. This study uses data-limited assessment methods to evaluate the population dynamics and stock status of this species in northern Tunisia (GSA 12). Growth parameters were estimated from size-frequency data, collected at Bizerte fishing port in 2025, using ELEFAN functions (Electronic LEngth Frequency ANalysis) implemented in the TropFishR package. Lengths at sexual maturity (Lm50 and Lm95) and natural mortality (M) were derived from empirical equations. Stock status was evaluated using the Catch MSY Monte Carlo model (CMSY++ model), which was applied to catch data from 1995 to 2024 and was complemented by length-based models (Length-based Bayesian Biomass “LBB”, the length-based indicator method “LBI” and length-Based Spawning Potential Ratio “LBSPR”), which used size data from 2024 and 2025. The best-fitting growth model (ELEFAN SA standard) yielded an asymptotic length (L∞) of 89.29 cm, a growth coefficient (K) of 0.369 year–1 and a growth performance index (φ') of 3.469, indicating moderate growth. The estimated lengths at maturity (Lm50 = 47.1 cm; Lm95 = 56.52 cm) suggest that L. piscatorius reaches sexual maturity at a relatively large size compared to its maximum size. Natural mortality (M = 0.19 year–1) was low, signifying that population dynamic was strongly influenced by fishing mortality rather than natural processes. The stock assessment results from CMSY++, LBB, LBI, and LBSPR provided complementary evidence on stock status, but did not allow a definitive conclusion regarding the sustainability of the stock. Estimates of B/BMSY > 1 (CMSY++ and LBB) and F/FMSY = 0.904 (CMSY++) suggest that fishing pressure remains below critical thresholds. Demographic indicators from LBI showed a proportion of mature individuals (Pmat = 0.4652) and proportion of mega-spawners (Pmega = 0.1015) were below the reference point, a moderate proportion of optimally sized individuals (Popt = 0.3975), suggesting that the size structure of the catch is not fully consistent with the reference pattern and that improvements in size selectivity may be beneficial. However, the LBSPR-derived spawning potential ratios (SPR = 39% in 2024 and 40% in 2025) are close to the recommended reference point of 40%, indicating that the stock is close to the limit of full reproductive sustainability, and any increase in fishing effort could compromise spawning biomass in the medium term. Overall, the L. piscatorius stock in GSA 12 should be considered to be operating close to several biological reference levels and a precautionary approach should be adopted to preserve the spawning stock and the population’s size structure.

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DOI: 10.3897/aiep.56.207218

Authors: Kunio Amaoka, Hsuan-Ching Hо, Yo Su

Abstract: Two species belonging to the genus Engyprosopon in the flatfish family Bothidae, exhibiting the reversed condition not only externally but also internally, were recently collected from southwestern Taiwan. A detailed description of each specimen is provided, and situs inversus is discussed. Previously, reversed specimens in the family Bothidae were extremely rare, with only three reported cases, whereas the reversed condition was commonly found in the families Paralichthyidae and Pleuronectidae. This rarity is possibly due to their low commercial value, which results in a low chance of detecting an inversion. Previously, it was thought that the family Bothidae was the most specialized group within the order Pleuronectiformes, making the reversed condition less likely to occur. However, this idea may need reevaluation, and the reversed condition in Bothidae may be more common than previously thought.

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DOI: 10.3897/aiep.56.198566

Authors: Ziyu Zhu, Hongyan Liu, Yongqiang Duan, Yi Chen, Siqi Zhang, Jiaqi Wang, Minghua Wang, Xiaohui Chen, Rui Duan, Shiyong Zhang

Abstract: To advance the efficient all-male breeding of channel catfish, Ictalurus punctatus (Rafinesque, 1818), this study utilized YY pseudofemales obtained through hormone-induced sex reversal. Morphological traits and body weight were systematically compared among YY pseudofemales (n = 50), XX females (n = 50), XY males (n = 50), YY supermales (n = 50), and XY pseudofemales (n = 50) at 6 months of age. Using correlation analysis, path analysis, and multiple regression, the relationships between morphological traits and body weight were elucidated. The results showed that YY pseudofemales exhibited significantly lower values for several morphological indicators than males, but no significant differences were observed relative to females or XY pseudofemales. This provides key phenotypic evidence supporting the feasibility of using YY pseudofemales as female broodstock in the “YY supermale × YY pseudofemale” breeding system. The analysis revealed strong correlations between morphological traits and body weight; however, the key traits affecting body weight showed significant population-specific patterns. Specifically, weight gain in pseudofemale channel catfish primarily depended on increased body depth at the anus, exhibiting a “body depth-dominant” pattern, whereas male channel catfish showed a “standard length-dominant” or “total length-dominant” pattern. This finding offers direct theoretical guidance for implementing precise population-differentiated selection strategies tailored to distinct breeding objectives. Furthermore, a reliable predictive model for body weight in YY pseudofemales was established based on key morphological traits. This model may facilitate early screening of broodstock and accelerate genetic progress in all-male breeding, although its broader applicability requires validation across independent populations and rearing systems.

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DOI: 10.3897/aiep.56.205677

Authors: Murat Kerim, Serap Ustaoğlu Tırıl

Abstract: Global fish oil production has plateaued while salmonid aquaculture expands, creating urgent demand for sustainable alternative lipid sources. This study evaluated the effects of replacing dietary fish oil with canola oil, safflower oil, and their blends on growth performance, feed utilization, condition indices, and muscle fatty acid composition in juvenile Black Sea trout, Salmo labrax Pallas, 1814. Seven isonitrogenous and isolipidic diets (45% crude protein, 18% crude lipid) differing only in lipid source—fish oil (FO), safflower oil (SO), canola oil (CO), and their 50:50 binary and equal ternary blends—were fed to triplicate groups of juvenile Black Sea trout (initial weight 30.22 ± 0.19 g) for 90 days. Growth performance, feed utilization, condition indices, and fatty acid compositions of diets and white dorsal muscle were determined. Growth performance and feed utilization did not differ significantly among treatments (P > 0.05), confirming that complete fish oil replacement did not compromise growth performance. However, significant differences were observed in fat deposition rate, viscerosomatic index, and hepatosomatic index (P < 0.05). Muscle fatty acid profiles closely mirrored dietary composition: saturated and n-3 long-chain polyunsaturated fatty acids (EPA, DHA) declined while monounsaturated and n-6 fatty acids increased with increasing plant oil inclusion. The muscle n-3/n-6 ratio fell most sharply in the safflower oil group. Economic analysis revealed that complete plant oil substitution reduced feed costs by 12%–13% compared to the fish oil control. Both canola and safflower oils can effectively replace fish oil in Black Sea trout diets without compromising growth. Canola oil emerges as the more broadly balanced substitute, while safflower oil’s strong n-6 enrichment restricts its suitability to blended or finishing strategies.

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DOI: 10.3897/aiep.56.199776

Authors: Sami Mili, Rym Ennouri, Siwar Agrebi, Safa Bejaoui, Maissa M. Morsi, Manel Ben Ali, Amor Hedfi

Abstract: Small tunas are economically important for Mediterranean fisheries. Yet they remain poorly assessed due to data limitations. This study provides the first quantitative stock assessment of little tunny, Euthynnus alletteratus (Rafinesque, 1810), and bullet tuna, Auxis rochei (Risso, 1810), in the central Mediterranean Sea (GSA 13) using two complementary data-limited methods. The Length-Based Bayesian Biomass (LBB) method was applied to length-frequency data collected in 2022 (408 E. alletteratus and 508 A. rochei), and the CMSY++ method was applied to the official landings time series from 1996 to 2022. The results reveal contrasting stock statuses. Auxis rochei is critically overfished, with current biomass at only 8% of unexploited levels (B/B0 = 0.08) and extremely high fishing mortality (F/M = 15). CMSY++ confirmed overfishing (B/BMSY = 0.52; F/FMSY = 1.30). Length structure analysis revealed that 42% of the catch were immature juveniles (32.6 cm). In contrast, E. alletteratus is also overfished, albeit less severely (B/B0 = 0.25; F/M = 1.4). CMSY++ results (B/BMSY = 0.75; F/FMSY = 1.39) and a low proportion of juveniles (2%) suggest a healthier demographic structure, although large spawners (>90 cm) are rare. Based on these findings, we recommend the following species-specific measures: for A. rochei, increase the minimum conservation reference sizes (MCRS) from 27 cm to the optimal 34 cm, and reduce fishing effort. For E. alletteratus, prohibit the landing of specimens measuring more than 80 cm, and increase the MCRS from 54 cm to 66 cm. This study demonstrates the feasibility of quantitatively assessing data-poor small tunas in the Mediterranean and provides essential baselines for their sustainable management.

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DOI: 10.3897/aiep.56.200819

Authors: Se Hun Myoung, Si-Won Choi, Byung-Jik Kim, Min-Su Woo, Chang-Soo Bae, Myeong-Jun Gwon, Yun-Bae Kim, Joo Myun Park

Abstract: A single specimen (41.9 mm SL) of Tomiyamichthys oni (Tomiyama, 1936), representing the family Gobiidae, was firstly recorded from Ulleung Island, Korea on 1 March 2025. It was characterized by clusters of irregular brown spots covering its body, and a black band on lower part of opercle extending forward to tip of chin. The species is morphologically similar to Tomiyamichthys elliotensis Allen, Erdmann et Dudgeon, 2023, but distinctly different in the presence of small, irregular brown spots on the body (absence these spots in T. elliotensis). In addition, T. oni was well distinguished from another four valid species in the genus Tomiyamichthys as determined by mitochondrial DNA cytochrome c oxidase subunit I gene (COI) sequence (546 bp) with genetic distances ranging from 0.130 to 0.252. In addition, this study reported a new northernmost record for the species at the latitude of 37°27'N. A Korean name ‘Geom-eun-tti-nun-se-u-mang-dug’ is herein proposed for the species.

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DOI: 10.3897/aiep.56.187971

Authors: Carlos Hiram Rábago-Quiroz, Adrián Felipe González-Acosta, Juan Antonio García-Borbón, Juan Gabriel Díaz-Uribe, Mariana Elisa Worbis-Badias, Joaquín David Magaña, Gorgonio Ruiz-Campos

Abstract: A thorough study of target species, including the collection of data on their life-history traits, is essential for quantitative assessment in fishery management and conservation programs to reduce the vulnerability of populations subject to fishing pressure. This study aimed to analyze the size composition, length–weight relationships, condition factors, and catch volume of four of the most frequent and commercially valuable species caught by small–scale fisheries operating in the Mexican Priority Marine Region 4 of the northwestern Pacific. The presently reported study was based on bycatch from shrimp trawls and commercial catches, and the data were analyzed jointly and separately. Sampling was conducted to obtain length and weight data for four selected fish species: California halibut, Paralichthys californicus (Ayres, 1859); finescale triggerfish, Balistes polylepis Steindachner, 1876; bullseye puffer, Sphoeroides annulatus (Jenyns, 1842); and the spotted sand bass, Paralabrax maculatofasciatus (Steindachner, 1868). A total of 3215 fish individuals were studied, most of which corresponded to the spotted sand bass coming from bycatch. Size-frequency distributions differed among species, with bycatch dominated by smaller size classes and artisanal commercial fisheries capturing larger individuals, reflecting differential ontogenetic habitat use and fishing-gear selectivity. The length–weight parameter b ranged from 2.70 in the bullseye puffer to 2.94 in spotted sand bass, indicating variation among species associated with the presence of both juvenile and adult individuals in the samples; negative allometric growth was consistent across pooled groups, with length increasing proportionally more than biomass. Relative condition factors exceeding 1.0 suggest favorable somatic growth conditions for all species and the capacity to assimilate available energy over extended periods. Size at first capture (L50) varied among species and groups and differed from published estimates of size at sexual maturity, while S. annulatus and Paralichthys californicus contributed most substantially to total catches during the study period. Overall, this assessment of size composition, length–weight relationships, condition factors, and catch data for the most frequent and commercially valuable species in the Bahía Magdalena–Almejas lagoon system, based on both bycatch and commercial fisheries, provides useful information for evaluating potential fishing impacts and reducing the vulnerability of exploited populations within this marine priority region.

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DOI: 10.3897/aiep.56.194083

Authors: Adem Sezai Bozaoğlu, Ekin Akoglu, Ercan Ateş

Abstract: Approximately 25% of annual inland capture fish production in Türkiye is from pearl mullet, Alburnus tarichi (Güldenstädt, 1814), which is an endemic species to the Lake Van Basin. Therefore, sustainable utilization of pearl mullet stocks in the basin carries utmost importance for the livelihoods of fishers and food provisioning in the region. Conventionally, fishery of pearl mullet is carried out with trammel and mono-filament gillnets. However, to date, the effectiveness of multifilament gillnets was not put to the test. Therefore, this study, which was conducted in Lake Van between September 2022 and April 2023, employed six sets of monofilament and multifilament gillnets with mesh sizes of 22, 23, and 24 mm to investigate the selectivity of gillnets comparatively. The nets were laid at depths ranging from 8 to 60 m, and 45 samples were collected. The SELECT method was used to calculate the selectivity parameters of the samples. The most suitable model for monofilament gillnets was the Normal Scale model, and the optimum capture lengths were 22.29, 22.75, and 23.18 cm. In multifilament gillnets, the most suitable model was the lognormal model, and the optimum capture lengths were 21.01, 21.99, and 22.24 cm. In both net sets, the month with the highest catch per unit of effort was April, with values of 83.32 kg/100 m/day in monofilament gillnets and 27.83 kg/100 m/day in multifilament gillnets. The results of this study indicated that the most suitable mesh size for pearl mullet fishing with gillnets in Lake Van is 24 mm. For pearl mullet fishery in Lake Van, the use of 24 mm monofilament gillnets compared to multifilament gillnets is recommended due to their high capture efficiency.

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DOI: 10.3897/aiep.56.199443

Authors: Xiuhui Tan, Yanfei Deng, Xuguang Li, Liqiang Zhong, Jun Zhou

Abstract: A novel intersex individual of the Chinese mitten crab, Eriocheir sinensis Milne-Edwards, 1853, sampled from Nanjing, eastern China was described herein. The specimen exhibited a fully typical female external phenotype. Its abdomen retained the characteristic circular shape unique to normal females, and the ratios of all measured morphological traits were consistent with the national standards of China for female E. sinensis individuals. A pair of female gonopores was present on the fifth thoracic somite, with the second to fifth pairs of ovigerous pleopods bearing normal setae. Notably, male first gonopods (G1) were observed in this individual, whereas the second gonopods (G2) and penis were absent. Potential hormonal or environmental causes (e.g., IAG/CFSH imbalance, EDCs) underlying this sexual aberration were further discussed. The findings of this study enrich the biological data on intersex phenomena in crustaceans and provide a fundamental reference for exploring the sex differentiation mechanism and environmental adaptation of E. sinensis under habitat disturbance.

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DOI: 10.3897/aiep.56.193569

Authors: Gilar Budi Pratama, Ismail Maqbul, Nurani Khoerunnisa, Faqih Baihaqi

Abstract: Skipjack tuna, Katsuwonus pelamis (Linnaeus, 1758), is an economically important pelagic species that supports small-scale fisheries in Palabuhanratu Bay, West Java, Indonesia. This study aimed to examine the relationship between physical oceanographic parameters {sea surface temperature (SST), salinity, sea surface height (SSH), and current speed} and biogeochemical parameters {chlorophyll-a (CHL), pH, and silicate} with skipjack catch per unit effort (CPUE) using a Generalized Additive Model (GAM) based on data collected during 2019–2023. The results indicate that variations in skipjack CPUE are associated with a combination of physical and biogeochemical oceanographic conditions. The best-performing model explained 70.7% of the deviance, with an adjusted R2 of 0.623 and an AIC (Akaike Information Criterion) value of 743.26. Response curves indicated that higher CPUE tended to be associated with lower sea surface temperature (marginally significant; P = 0.068), lower salinity, higher chlorophyll-a concentrations, and variation in pH, while several other oceanographic variables exhibited non-linear relationships with CPUE. Model selection results further showed that the model integrating both physical and biogeochemical parameters outperformed models based on either group of variables alone. These findings highlight the importance of considering multiple environmental factors simultaneously when examining CPUE variability in small-scale skipjack fisheries. However, the results represent statistical associations between environmental variability and fishery-dependent catch rates and should not be interpreted as definitive evidence of skipjack tuna habitat suitability.

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DOI: 10.3897/aiep.56.197412

Authors: Se-Yeon Park, Seung-Woon Yun, Eon-Jong Kang, Jong-Young Park

Abstract: Misgurnus mohoity (Dybowski, 1869) is recorded for the first time from the Korean Peninsula based on specimens collected from South Korea. It is distinguished from other Korean Misgurnus by the following characteristics: 48–50 total vertebrae; 19–20 caudal vertebrae; 164–180 lateral line scales; a poleaxe-shaped lamina circularis with a shallow neckline at the base in mature males; and a slender, elongated caudal peduncle with a CPL/CPD (caudal peduncle length/caudal peduncle depth) ratio of > 1.7 and an LPC/DPA (the projected length from the posterior edge of the anal fin base to the base of the caudal fin to the projected length from the pelvic fin insertion point to the anterior edge of the anal fin base) ratio of > 1.1. Mitochondrial cytb gene analysis revealed that the Korean specimens form a monophyletic clade (100% bootstrap support) with populations from Russia, China, and North Korea, exhibiting a high genetic distance (K2P: 10.04%) from other Korean congeners. A new Korean name, “Ga-neun-mi-ggu-ri”, is proposed based on the slender and elongated shape of the body and caudal peduncle. These findings provide crucial biogeographical evidence for understanding the dispersal and differentiation of the genus Misgurnus in Northeast Asia.

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DOI: 10.3897/aiep.56.197471

Authors: Kota Obata, Yuto Mizumoto, Toshio Kawai, Hidetoshi Wada

Abstract: Poecilopsetta colorata Günther, 1880 and Poecilopsetta praelonga Alcock, 1894, deep-sea flatfishes belonging to the family Poecilopsettidae (Teleostei, Pleuronectiformes), are recorded for the first time from Japan, based on two specimens of the former and one of the latter, all collected from the Pacific coast of southern Japan. The diagnostic characters of each species are reassessed. The former specimens, from the Enshu-nada Sea and Tosa Bay, were identified as P. colorata by a combination of the following characters: dorsal-fin rays 48–62; anal-fin rays 46–53; ocular-side pectoral-fin rays 9–12; lateral-line scales 90–124; body deep; eyes separated by flat scaled interorbital area; middle pectoral-fin rays on ocular side branched; and single large dark blotch on ocular-side pectoral fin. A second specimen from the Enshu-nada Sea was identified as P. praelonga, having the following diagnostic characters of that species: dorsal-fin rays 57–65; anal-fin rays 45–55; ocular-side pectoral-fin rays 6–11; lateral-line scales 91–111; body slender; eyes contiguous; all pectoral-fin rays simple on both sides; straight section of lateral line about three times length of lateral-line curve width; pectoral fin uniformly black. The specimens from the Enshu-nada Sea represent the northernmost records for each species, P. colorata and P. praelonga having been previously recorded only as far north as the South China Sea off Hong Kong, and from southern Taiwan, respectively. It is likely that the ocular-side head and body coloration of P. colorata and the caudal-fin coloration of P. praelonga are variable intraspecifically, whereas the presence or absence of branched ocular-side pectoral-fin rays is species-specific in Poecilopsetta. The presently reported specimens are likely to have been transported by the Kuroshio Current while at the pelagic larval stage, thereafter, settling near their collection sites, due to having remnants of blind-side black spots, which are distinct in larval and juvenile Poecilopsetta, but tend to disappear with growth.

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DOI: 10.3897/aiep.56.197399

Authors: Yo Su, Chia-Hao Chang, Hsuan-Ching Ho, Van Quang Vo, Chien-Hsiang Lin

Abstract: Two species of cusk eels, Neobythites nanhaiensis Chen, Zhao, Yang, Zhang, He, Zhang, Wang et Zhong, 2026 and Grammonus robustus Smith et Radcliffe, 1913 are reported based on specimens collected from Nha Trang, Vietnam. The specimens of N. nanhaiensis represent the northernmost record of this species and the specimen of G. robustus fills the distribution gap between the Philippines and eastern Australia. Detailed descriptions of both species and sagittal otoliths are provided and compared to data of other specimens. Moreover, we found that the original description of N. nanhaiensis was partly based on damaged specimens (tail regenerated), making the counts of dorsal-, anal-, and caudal-fin rays, and vertebrae, and some measurements unreliable, and the true variation of this species remains unknown.

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DOI: 10.3897/aiep.56.194913

Authors: Kunto Wibowo, Djohan Tjiptadi, Wiwi Tarmini, Ruby V. Kusumah, Agus Priyadi, Sekar Larashati, Mey R. Widoretno, Dwi Febrianti, Selvia Oktaviyani, Dian Oktaviani, Gema Wahyudewantoro, Rizki A. Wijaya, Hilda M. Pratiwi, Teguh Peristiwady

Abstract: Specimens of marine ornamental fishes collected from western Sumatra, Indonesia, were examined and several noteworthy records are documented here. Apolemichthys xanthurus (Bennett, 1833), Centropyge flavipectoralis Randall et Klausewitz, 1977, Abudefduf caudobimaculatus Okada et Ikeda, 1939, and Siganus magnificus (Burgess, 1977) represent the first voucher-based records of these species from this region, and their distributional records are discussed. In addition, xanthochromic individuals of Epinephelus quoyanus (Valenciennes, 1830) and Paracanthurus hepatus (Linnaeus, 1766) are documented for the first time.

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DOI: 10.3897/aiep.56.190543

Authors: J. Pragatheesh Kumar, Sivakumar Ragul, M. K. Sajeevan, Ronald Fricke

Abstract: The South African bigeye dragonet, Synchiropus monacanthus Smith, 1935 (family Callionymidae), is reported for the first time from Indian waters based on six female specimens (68.2–104.5 mm SL) collected from trawl bycatch off Pudukkottai, southeastern India (Palk Bay). This record extends the known distribution of S. monacanthus eastward by approximately 2500 km from its previously documented range in the western Indian Ocean (South Africa, Mozambique, Madagascar, Tanzania, Socotra Archipelago). The specimens were collected at a depth of approximately 100–150 m, which is shallower than the previously reported bathymetric range of 175–428 m for this species, providing new information on its habitat depth. Comparative morphological data are provided to distinguish S. monacanthus from its congener, Synchiropus lineolatus (Valenciennes, 1837), which is also recorded from Indian waters. This finding adds a second species of Synchiropus to the Indian marine ichthyofauna and highlights the value of examining deep-water trawl bycatch for documenting species distributions.

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DOI: 10.3897/aiep.56.190030

Authors: Elsie Y. Guibone, Sanny David P. Lumayno, Rex Ferdinand M. Traifalgar, Victor Marco Emmanuel N. Ferriols, Carmelo S. del Castillo

Abstract: Naujan white goby, Glossogobius aureus Akihito et Meguro, 1975, an economically important freshwater fish native to Naujan Lake, Oriental Mindoro, has previously been reported to harbor the parasitic copepod Lernaea cf. cyprinacea Linnaeus, 1758 in captivity; however, a year-round epidemiological assessment in the wild has not yet been conducted. This study assessed 1247 fish collected from Naujan Lake from May 2024 to April 2025 to determine prevalence, mean intensity, mean abundance, length–weight relationship, and condition factor in both infected and uninfected individuals. A total of 180 infected G. aureus cases were recorded (14.4% prevalence), with infections occurring year-round, peaking from May to June during the warmest ambient temperatures in Naujan, and declining in cooler periods from October to February. Parasite abundance differed significantly between seasons and increased with host size, with larger individuals harboring higher parasite loads. Spatial distribution heatmaps indicated that L. cf. cyprinacea predominantly attached to the dorsal and pectoral fins across seasons, with increased occurrence on the gill and opercular regions during the wet season, i.e., well-vascularized and protected sites that facilitate attachment and feeding. Both infected and uninfected G. aureus exhibited negative allometric growth (b < 3) over seasonal periods, with infected individuals showing significant variation in weight relative to length. Parasitic infection may influence host growth and body condition, with greater growth variability during the dry season and changes in condition potentially linked to environmental stress and the host’s reproductive activity. The year-round occurrence of infection, with peak levels during warmer months, has important implications for the collection of G. aureus broodstock, a species currently being developed for aquaculture. Collecting broodstock smaller than 10 cm during cooler months may reduce parasite transmission under culture conditions. Overall, these findings provide baseline information for parasite management and support the development of health management strategies for emerging G. aureus culture in freshwater systems. This study represents the first year-round epidemiological assessment in a tropical wild freshwater goby population in Southeast Asia.

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DOI: 10.3897/aiep.56.184586

Authors: Ludevito S. Batilong, Cyril Tom B. Ranara, Sanny David P. Lumayno, Dennis D. Tanay, Carmelo S. del Castillo, Alan N. Failaman, Rex Ferdinand M. Traifalgar

Abstract: The rising cost and limited availability of fishmeal have prompted the search for sustainable protein alternatives in aquaculture feeds. This study evaluated the potential of shrimp head meal (SHM), a locally available byproduct of shrimp processing, as a substitute for fishmeal in practical diets for nursery-culture milkfish, Chanos chanos (Fabricius, 1775) fry. Five experimental diets were formulated with graded levels of SHM replacing sardine fishmeal (0%, 25%, 50%, 75%, and 100%) and fed to fry for eight weeks. Growth performance, feed utilization, carcass composition, and nutrient retention were assessed. Results showed that partial replacement of fishmeal with SHM at 25% supported growth, feed conversion efficiency, protein efficiency ratio, and survival rates comparable to the control diet. At higher inclusion levels (≥50%), significant reductions in weight gain, feed efficiency, and survival were observed, although carcass protein content increased, while lipid deposition declined. Protein retention was enhanced at moderate SHM levels, whereas lipid retention decreased consistently with increasing inclusion. These findings suggest that SHM can effectively replace up to 25% of fishmeal in milkfish fry diets, offering a cost-effective and environmentally sustainable alternative. However, higher inclusion levels (≥50%) were associated with reduced growth performance, feed conversion efficiency, and survival, indicating possible limitations in the nutritional balance of SHM when used as a major protein source. The study highlights the potential of SHM as a locally sourced feed ingredient and recommends further research on processing methods to improve its nutritional value and applicability in aquaculture.

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DOI: 10.3897/aiep.56.191711

Authors: Mónica Jimena Juárez-Maldonado, Luis Fernando Del Moral-Flores

Abstract: We studied the morphological variation of the chain dogfish, Scyliorhinus retifer (Garman, 1881), to demonstrate sexual dimorphism based on 15 adult males {434–557 mm total length (TL)} and 10 adult females (437–556 mm TL) captured in the southern Gulf of Mexico. We took 60 morphological measurements, 12 of which showed significant differences between the sexes. Analysis of dermal denticle (DDs) density and shape showed variation by sex in the four regions: dorsal (females: 105–353 mm–2; males: 112–530 mm–2), ventral (females: 142–456 mm–2; males: 168–488 mm–2), lateral (females: 93–396 mm–2; males: 96–380 mm–2), and anterior dorsal (females: 209–490 mm–2; males: 254–534 mm–2). There were also significant differences within the same sex in the length of the DDs of the dorsal region, the length of the DDs of the anterior dorsal region, the width of the DDs of the anterior dorsal region, and the length and width of the DDs of the lateral region.

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DOI: 10.3897/aiep.56.188432

Authors: Cenk Sait Sert, Ali Yildirim Korkut, Kutsal Gamsiz, Bilge Karahan, Emel Özcan-Gökçek, Sule Gurkan, Serhat Engin, Mustafa Tolga Tolon, Ulviye Karacalar, Adnan Tokaç

Abstract: This study compared the growth performance, feed conversion efficiency, and genetic diversity of gilthead seabream, Sparus aurata Linnaeus, 1758, of Atlantic and Mediterranean origin reared under the same cage farming conditions for 15 months. Genetic variability was assessed using microsatellite and RAPD markers between groups. The results showed that the Atlantic group tended to exhibit higher final weight, specific growth rate (SGR), and improved feed conversion ratio (FCR) than the Mediterranean group. However, although these differences were initially significant (P < 0.05), they were not statistically significant after False Discovery Rate (FDR) correction (adjusted P > 0.05). Survival rates were similar across the groups. Genetic analyses revealed high within-population diversity in both groups, with moderate differentiation between Atlantic and Mediterranean origins, indicating a distinct but not strongly divergent genetic background. Overall, the results suggest a consistent trend toward improved growth performance in Atlantic seabream under the tested conditions; however, due to the lack of statistical significance after correction, cautious interpretation of the results is required. Further multi-environmental studies are required to confirm whether these trends reflect the true genetic advantages relevant to aquaculture and selective breeding programs.

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DOI: 10.3897/aiep.56.189167

Authors: Nihat Yeşi̇layer, Server Bektaş, Zafer Karslı, Arda Yıldırım

Abstract: This study investigated the effects of adding glandless cottonseed kernel powder (GCKP) to the diets of juvenile goldfish, Carassius auratus (Linnaeus, 1758), as an alternative plant protein source to fishmeal, examining its impact on growth performance and feed consumption. Four experimental groups were established, including control and treatments with 5%, 7.5%, and 10% GCKP, across 12 aquariums in 3 replications. Each aquarium housed 15 juvenile goldfish, totaling 180 fish, which were fed twice daily under a controlled feeding regime for a 90-day period. The initial mean live weight of the fish was 1.25 ± 0.03 g. At the end of the trial, the group with 5% GCKP reached the highest mean live weight of 3.722 ± 0.218 g, followed by the 10% GCKP group with 3.683 ± 0.219 g, the control group with 3.666 ± 0.253 g, and the 7.5% GCKP group with 3.422 ± 0.211 g (P > 0.05). Statistical analysis found no significant (P > 0.05) differences in live weight gain, specific growth rates, survival rates, feed consumption values, and feed conversion ratio (FCR) beteen the control group and the GCKP groups (5%, 7.5%, and 10%). The findings indicate that GCKP can be safely included in the diets of juvenile goldfish at levels up to 10% without any adverse effects on growth performance, feed utilization parameters, and survival rates.

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DOI: 10.3897/aiep.56.165790

Authors: Behzad Gholjaei, Rahman Patimar, Hojjatallah Jafaryan, Hadi Raeisi, Arsalan Bahalkeh

Abstract: In the summer of 2024, an unrecognized mullet species was reported to occur in considerable abundance in the shallow areas of the southeastern Caspian Sea. Since accurate species identification is essential for ecological monitoring, 65 specimens were collected using gillnets in late summer and early autumn 2024, and their morphological traits were examined to identify the species. The specimens correspond to the abu mullet, Planiliza abu (Heckel, 1843), a member of the family Mugilidae native to the subtropical waters of southern Iran (the Persian Gulf and the Sea of Oman). Additional surveys indicated that this species has spread into some inland ecosystems as well as the coastal areas of the Caspian Sea. Therefore, this paper reports the first record of an established population of abu mullet in the southern Caspian region, expanding the species’ known distribution northward toward a cold temperate climate, beyond its previously known range in southern Iran. The considerable occurrence rate in mullet catches, good body condition (CF > 1), large size (length and weight), and age of the collected specimens from the coasts of the southeastern Caspian Sea allow us to confidently state that this species has established a self-sustaining population in this sea, with the potential to successfully adapt to Caspian environmental conditions. Ongoing investigations are expected to reveal additional occurrences of abu mullet in the Iranian waters of the Caspian Sea.

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DOI: 10.3897/aiep.56.186812

Authors: Gustavo F. de Carvalho-Souza, Cristóbal Lobato Gómez, Enrique González-Ortegón

Abstract: The Benguela hake, Merluccius polli Cadenat, 1950, is a demersal species typically distributed along the Atlantic coast of Africa, ranging from Angola to Mauritania. This study reports the first confirmed records of M. polli in the Gulf of Cádiz (NE Atlantic), suggesting a northward expansion of this tropical-affinity species. Two specimens were caught by commercial trawlers in 2022: one (47 cm TL) on 17 February, and a second (62 cm TL) on 27 July. Both individuals were identified based on meristic characters and caudal fin pigmentation. To contextualize these findings, we analyzed fisheries auction data (IDAPES) from 2000 to 2024. While M. polli is a new occurrence in the local wild ichthyofauna, it is commercially abundant in the region because it is landed in Spanish ports by national vessels operating in Northwest African fishing grounds. Analysis of recent sales notes (2022–2024) confirms that M. polli constitutes the dominant fraction (>95%) of the “black hakes” caught in African fishing grounds, which were historically pooled with Merluccius senegalensis Cadenat, 1950 in fishery statistics. Economic analysis reveals that black hakes maintain a stable, lower-price market niche compared to the local European hake, Merluccius merluccius (Linnaeus, 1758). These findings support the trend of tropicalization in the Gulf of Cádiz and highlight the importance of accurate species identification in commercial landings.

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DOI: 10.3897/aiep.56.181178

Authors: Guoyang Liu, Di Peng, Hanye Zhang, Dan Song, Biyuan Liu, Qiqun Cheng

Abstract: The complete mitochondrial genome of Acheilognathus imberbis Günther, 1868, a small freshwater fish inhabiting tributaries of the Yangtze and Yellow River systems, was sequenced and characterized. The circular mitogenome spans 16 576 base pairs, containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a non-coding control region. Nucleotide composition analysis revealed an AT-rich genome (A + T = 58.93%) with distinct guanine deficiency (15.88% G content), consistent with a typical vertebrate mitogenome bias. To resolve debated phylogenetic relationships within Acheilognathinae, we performed phylogenetic analysis using concatenated sequences of 13 PCGs from 37 representative species. Results confirmed the monophyly of Acheilognathinae, which diverged into two primary clades: Acheilognathus and the Tanakia–Rhodeus complex. Notably, the monophyletic status of Rhodeus received limited nodal support, suggesting potential taxonomic revisions. Pairwise genetic distances (Tamura–Nei model) ranged from 0.0071 to 0.2600 across the subfamily. Through homology analysis, some Acheilognathinae fishes are clustered together, and the genetic distance is much less than 0.0406, suggesting re-evaluation of their classification criteria. Positive selection analysis based on the ND2 gene using site models revealed no statistically significant codon positions under positive selection. This mitogenomic resource advances molecular systematics and evolutionary studies in Acheilognathinae fishes.

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DOI: 10.3897/aiep.56.184228

Authors: Jeong-Soo Gim, Mu Sung Sung, Donghyun Hong, Gea-Jae Joo, Dong-Kyun Kim, Hyunbin Jo

Abstract: Length–weight relationships (LWR) were estimated for 21 fish species sampled from southeastern Gyeongsangnam-do, South Korea, including the Ulju basin (Yangsan and Hoeya rivers) and the Miryang River system (Miryang River and Danjang Stream). The following species were studied: Carassius auratus (Linnaeus, 1758); Rhodeus uyekii (Mori, 1935); Acheilognathus majusculus Kim et Yang, 1998; Pseudorasbora parva (Temminck et Schlegel, 1846); Pungtungia herzi Herzenstein, 1892; Coreoleuciscus aeruginos Song et Bang, 2015; Squalidus multimaculatus Hosoya et Jeon, 1984; Rhynchocypris oxycephala (Sauvage et Dabry de Thiersant, 1874); Zacco platypus (Temminck et Schlegel, 1846); Misgurnus mizolepis Günther, 1888; Koreocobitis naktongensis Kim, Park et Nalbant, 2000; Iksookimia longicorpa (Kim, Choi et Nalbant, 1976); Niwaella multifasciata (Wakiya et Mori, 1929); Liobagrus mediadiposalis Mori, 1936; Oryzias latipes (Temminck et Schlegel, 1846); Coreoperca herzi Herzenstein, 1896; Lepomis macrochirus Rafinesque, 1819; Micropterus salmoides (Lacepède, 1802); Odontobutis platycephala Iwata et Jeon, 1985; Odontobutis interruptus Iwata et Jeon, 1985; Acanthogobius flavimanus (Temminck et Schlegel, 1845). LWR data for four species, have not previously been reported in FishBase (A. majusculus, K. naktongensis, N. multifasciata, L. mediadiposalis) while those for 12 additional species were available in limited numbers (1–4 records). Among species with sufficient sample sizes (n ≥ 20), six species exhibited negative allometric growth (b < 3) and one showed isometric growth (b ≈ 3). The values of coefficient a ranged from 0.0020 to 0.0166. For species with n ≥ 20, b ranged from 2.80 to 3.03; for species with n < 20, b was fixed at 3.0. All species showed high correlation coefficients (r2 > 0.95).

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DOI: 10.3897/aiep.56.187582

Authors: Nika Ugrin, Mišo Pavičić, Iva Žužul Vrgoč, Branko Dragičević

Abstract: A specimen of the smalleye squaretail, Tetragonurus cuvieri Risso, 1810, was caught on 16 February 2024 (TL = 37.2 cm, W = 277.56 g) by trawl net at approximately 100 m depth in the Mljet Channel, between the islands of Lopud and Šipan (Croatian coast). This represents the first well-documented record of T. cuvieri in the whole Adriatic Sea. Although the species has been mentioned in the checklist of Albanian fishes pertaining to Adriatic waters previously, no supporting data were provided to confirm its occurrence. The specimen was identified based on morphological characters supported by molecular analysis. Morphological and biological data are presented herein. As information on the biology, ecology, and distribution of this species in the Mediterranean Sea remains scarce, this finding extends its known range and contributes to the growing number of rare or poorly known species recently recorded in the Adriatic Sea.

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DOI: 10.3897/aiep.56.188503

Authors: Ilija Ćetković, Jacopo Bernardi, Pero Ugarković, Alessandro De Maddalena, Branko Dragičević, Zdravko Ikica, Ana Pešić

Abstract: The great white shark, Carcharodon carcharias (Linnaeus, 1758), is a well-known predatory species that inhabits a wide geographic range, including the Adriatic Sea. A marked decline in the abundance of its Mediterranean population has been documented over recent decades, making research on this species in its natural environment increasingly difficult. This study documents two contemporary records of young-of-the-year individuals recorded in 2018 and 2025 off the coasts of Croatia and Montenegro, respectively. Both records were sourced from local fisheries and were subsequently reported to scientists through citizen science. The individual reported from Montenegro was photographed and released unharmed while still in the water. This study further highlights the importance of citizen science in documenting occurrences of elusive elasmobranchs such as the great white shark and in educating fishers through a bottom-up approach. Together with the recently recorded young-of-the-year specimen in this area, these observations suggest that the Eastern Adriatic Sea may represent a contemporary nursery area for the great white shark, although this hypothesis remains to be verified.

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DOI: 10.3897/aiep.56.187895

Authors: Da Yeon Kang, Joo Myun Park, Seong Yong Moon, Gun Wook Baeck

Abstract: This study examined the feeding ecology of Lateolabrax japonicus (Cuvier, 1828) in Korean coastal waters, focusing on variations in diet composition across the reproductive seasons and size classes of the fish. The stomach contents of 310 individuals were analyzed, and prey biomass was quantified and standardized to assess multivariate dietary pattern analyses. The primary prey of L. japonicus were teleost fishes, exhibiting a relative importance index of 92.8%. In the Teleostei prey group, Engraulis japonicus was the most dominant. Across all reproductive seasons and size classes, the diets were strongly dominated by teleost fishes, confirming the species’ position as a specialized piscivorous predator. The contribution of Teleostei increased from 85.2% during the non-spawning season to 96.2% during the spawning season, whereas that of Caridea shrimps declined markedly. Ontogenetic shifts were evident, with small individuals (<40 cm) relying more on Caridea shrimps and larger individuals exhibiting near-exclusive piscivory, reflecting size-dependent foraging consistent with energetic optimization. DistLM revealed that size class, reproductive season, total length and month significantly influenced dietary variation (P < 0.05), whereas no significant differences were detected between sexes. Overall, these findings demonstrate that L. japonicus maintains a relatively stable trophic niche, with minor temporal variation driven primarily by changes in the relative contribution of crustacean prey, highlighting its ecological role as a top-level piscivore and providing valuable insights for ecosystem-based management of coastal fish populations.

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DOI: 10.3897/aiep.56.185183

Authors: Francesco Tiralongo, Paola Leotta, Helen Accolla, Daniele Tibullo, Alberto Felici

Abstract: The portunid crab, Gonioinfradens giardi (Nobili, 1905), native to the Red Sea and the Indian Ocean, is one of the recent alien decapods expanding in the Mediterranean Sea. Following the first confirmed Italian record from Portopalo di Capo Passero in November 2025, here we documented 11 additional specimens collected between November 2025 and January 2026 from the Ionian coast of Sicily. These repeated occurrences over a short time period and within a relatively small area strongly suggest that the species is no longer an occasional arrival, but at an early phase of local establishment in the central Mediterranean. These records represent the species’ westernmost occurrence and highlight the need for targeted monitoring of alien portunids in the Mediterranean.

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DOI: 10.3897/aiep.56.182678

Authors: Nurfakhira Lani, Gun Wook Baeck, Jae Mook Jeong, Sang Jin Ye, Da Yeon Kang, Joo Myun Park

Abstract: Seagrass beds are vital marine ecosystems that provide habitat and resources for diverse fish communities. This study evaluated the effects of spatial and seasonal seagrass vegetation on fish assemblages inhabiting seagrass (Zostera marina Linnaeus, 1753) beds around Myeongsa (typically a sandy shore) and Daepo (denser seagrass beds) in the southern coastal region of Geoje Island. Fish samples were collected monthly from September 2009 to November 2010 using a beach seine and push net. A total of 51 fish species (42 species at Myeongsa and 36 species at Daepo) from 31 families were identified across both study sites. The two study sites exhibited distinct seagrass vegetation patterns, with denser seagrass at Daepo and relatively sparse seagrass at Myeongsa. At Myeongsa, Takifugu niphobles (Jordan et Snyder, 1901), Aulichthys japonicus Brevoort, 1862, and Syngnathus schlegeli Kaup, 1856 were the most dominant species (in terms of frequency of occurrence). In contrast, Daepo was dominated by Rudarius ercodes Jordan et Fowler, 1902, Hexagrammos agrammus (Temminck et Schlegel, 1843), and Paracentropogon rubripinnis (Temminck et Schlegel, 1843), highlighting habitat-specific differences between fish assemblages and common fish species. Fish species richness, abundance, and diversity varied substantially depending on habitat type and season. Myeongsa, which was dominated by Takifugu niphobles, had the highest fish abundance, whereas Daepo exhibited a more balanced and diverse species composition. Non-metric multidimensional scaling analysis further demonstrated that habitat and season significantly influenced fish assemblage structure, with seasonal variations in abundance correlating with changes in seagrass biomass and temperature. Our findings provide baseline data for the conservation and management of seagrass-associated fish communities in Korea and contribute to broader efforts to sustain biodiversity within coastal habitats.

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DOI: 10.3897/aiep.56.178433

Authors: Edward Hu, Todd W. Miller, Johanna J. Page

Abstract: Changing ocean conditions in higher latitude ecosystems and the potential impact on marine fish underscores the need for baseline information on their biology and growth. Here we present length weight regression (LWR) results of 12 species of fish from coastal, estuarine and lagoon waters of the eastern Bering, Chukchi, and Beaufort seas: Myoxocephalus scorpioides (Fabricius, 1780); Myoxocephalus quadricornis (Linnaeus, 1758); Myoxocephalus scorpius (Linnaeus, 1758); Gymnocanthus tricuspis (Reinhardt, 1830); Lumpenus fabricii Reinhardt, 1836; Lumpenus sagitta Wilimovsky, 1956; Osmerus dentex Steindachner et Kner, 1870; Hypomesus olidus (Pallas, 1814); Mallotus villosus (Müller, 1776); Liopsetta glacialis (Pallas, 1776); Pungitius pungitius (Linnaeus, 1758); Diaphus theta Eigenmann et Eigenmann, 1890. Of the species examined, four were in the family Cottidae, three in Osmeridae, two in Stichaeidae, and one each in Gasterosteidae, Myctophidae, and Pleuronectidae. Results showed the LWR coefficient b was significantly >3 for all cottids (sculpins) and osmerids (smelts), indicating positive allometric growth. One species (L. fabricii) in Stichaeidae had a b significantly >3, with the other species (L. sagitta) being significantly <3. The one species in Gasterosteidae (stickleback, P. pungitius) and Myctophidae (lanternfish, D. theta) also showed significantly <3, indicating negative allometric growth. Of the species examined, this is the first reporting of LWR results for Arctic sculpin (M. scorpioides).

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DOI: 10.3897/aiep.56.177135

Authors: Phiphat Wongmanee, Janejit Khudamrongsawat, Tassapon Krajangdara, Wansuk Senanan, Thadsin Panithanarak, Ratima Karuwancharoen, Wanlada Klangnurak

Abstract: Stingrays of the genus Brevitrygon in Thailand are captured as bycatch in fisheries, and a proportion of the catch is used for local consumption, but information on their biodiversity remains limited. This study examines the diversity of Brevitrygon species collected from the Gulf of Thailand and the Andaman Sea. A total of 148 specimens were morphologically identified as either Brevitrygon heterura (Bleeker, 1852) or Brevitrygon cf. imbricata, based on diagnostic characters. Morphometric analysis revealed that all specimens more closely resembled B. heterura, with no significant differences between morphotypes or sexes. Genetic analysis based on COI sequences from 39 samples further supported these results. All samples grouped within the B. heterura clade with strong bootstrap support and formed two distinct genetic subgroups corresponding to the Gulf of Thailand and the Andaman Sea. The mean intraspecific divergence (1.08%) fell within the expected range for population-level variation in elasmobranchs, with interspecific divergence from other Brevitrygon species exceeding 9%. These results indicate that B. heterura in Thai waters likely represents a single species. While both morphometric and genetic data suggest regional differentiation, the observed variation falls within the normal range for a single species, providing no evidence of cryptic diversity. This study underscores the value of integrating morphological and molecular data to better understand population structure and taxonomy in stingrays.

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DOI: 10.3897/aiep.56.181255

Authors: Sivakumar Ragul, M. Balaganesan, K. K. Karuppasamy, R. Durairaja, N. Jayakumar, Ronald Fricke

Abstract: The Japanese spiny dragonet, Callionymus draconis Nakabo, 1977, a member of the subgenus Callionymus (Spinicapitichthys), was previously known only from the eastern Indian Ocean and the western Pacific, with records from southern Japan and Western Australia. This study reports the first record of C. draconis from India, based on a single male specimen (71.0 mm SL) collected from trawl bycatch off Kanyakumari, Tamil Nadu, southeastern Arabian Sea (southernmost port in India). This finding represents a significant westward range extension of approximately 5200 km, establishing the westernmost known limit of the species distribution. Furthermore, the collection depth of 80 to 100 m constitutes the shallowest recorded occurrence for this species, indicating a broader bathymetric range than previously known. This record bridges a major biogeographical gap in the known distribution of C. draconis, enriches the documented marine fish diversity of India, and highlights the importance of bycatch surveys in revealing cryptic marine biodiversity and refining the understanding of Indo-Pacific fish biogeography.

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DOI: 10.3897/aiep.56.157418

Authors: Muhammad Imran, Farhat Jabeen

Abstract: This study validated morphometric and genetic approaches to evaluate the population structure and genetic diversity of three endangered and economically significant catfish species: Bagarius bagarius (Hamilton, 1822); Clupisoma garua (Hamilton, 1822); and Eutropiichthys vacha (Hamilton, 1822), in the riverine system of Punjab (Chenab, Indus, and Jhelum rivers), Pakistan. This study aimed to create a reliable method for fish identification and to provide critical standard data for their conservation. Fish samples from the designated riverine populations were morphologically identified and then authenticated through DNA barcoding and phylogenetic analysis using mitochondrial cytochrome c oxidase subunit I (COI) gene sequence. Principal component analysis (PCA) suggests a clear relationship between species and morpho-meristic characteristics. Maximum Likelihood (ML) trees were constructed using MEGA 11 under the K2P model. The dataset for the ML analysis included reference COI sequences from the confamilial and congeneric species. Findings of morphometric analysis showed a distinct morphological variation in all species, especially Bagarius bagarius, showing a unique profile. This finding was powerfully corroborated by genetic analysis of the COI gene, which confirmed three distinct genetic groups corresponding to the three species. The mean interspecific genetic divergence was a substantial 0.112, while intraspecific variation was minimal (0.001–0.002). This study utilizes a crucial and accurate identification method for these endangered catfish species. DNA barcoding proved to be a highly effective and reliable tool for confirming the identification of these catfish species, complementing and validating our findings of traditional morphological methods. Information on population structure and genetic variation obtained from the presently reported study is helpful for providing essential foundational data for informing conservation efforts and fisheries management in the region and highlighting the power of an integrated approach for species assessment.

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DOI: 10.3897/aiep.56.172292

Authors: Chiara Lubich, Gisellen Mc Comb, Flávia Siqueira-Souza, Carlos Freitas

Abstract: Ageneiosus lineatus Ribeiro, Rapp Py-Daniel et Walsh, 2017 is a medium-sized catfish widely distributed in the Amazon and Orinoco basins. Despite its ecological relevance and potential in the ornamental fish trade, little is known about its biology. This study aimed to describe the feeding ecology, reproductive traits, and population condition of the species in the middle Negro River. Standardized sampling was conducted in three hydrological periods between 2016 and 2019, resulting in 164 individuals analyzed. The species showed predominantly nocturnal activity, a carnivorous diet with strong piscivory tendency (AIi > 94% in females). Females reached larger sizes than males, although males matured at slightly smaller lengths. The wide size range (7.50–18.0 cm) and condition factor (Kn > 1) indicate a healthy population. Although gonadal activity was recorded during high water, the limited sampling intervals prevented inference on reproductive seasonality. These findings highlight the ecological role of sedentary Amazonian catfishes and reinforce the need to incorporate them into adaptive management and conservation strategies.

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DOI: 10.3897/aiep.56.174662

Authors: Thi Diem Quynh Nguyen, Hoang Duy Minh Le, Thao Nguyen Nguyen, Quoc Vu Vo, Thai Duong Le, Van Tan Phan, Nguyen Thuy Trang Pham, Hoang Nhat Minh Nguyen, Ty Nguyen, Thi Hao Nguyen, Thi Phuong Anh Vu, Van Giang Tran

Abstract: The Tam Giang Lagoon in central Vietnam is one of the largest coastal lagoon ecosystems in Southeast Asia, playing a role in maintaining regional fish biodiversity and supporting local fisheries. However, knowledge about the ecological adaptation and genetic structure of key fish species in this system remains limited. This study investigated the morphological variation, trophic ecology, and mitochondrial genetic diversity of three ecologically and economically important species Terapon jarbua (Forsskål, 1775); Acanthopagrus latus (Houttuyn, 1782); and Oxyurichthys ophthalmonema (Bleeker, 1856). Morphometric and meristic analyses revealed clear interspecific differentiation in body depth, fin configuration, and scale counts, reflecting adaptive divergence across distinct habitat zones within the estuarine–lagoon continuum. Dietary analyses, based on gut morphology and nutritional composition, indicated feeding strategies ranging from omnivory to carnivory. Terapon jarbua exhibited a generalist omnivorous habit exploiting both planktonic and benthic resources, A. latus showed predominantly benthic feeding behavior, whereas O. ophthalmonema displayed strong carnivory, consuming mainly small fishes and crustaceans. Mitochondrial COI and CR analyses revealed high haplotype diversity and distinct nucleotide composition patterns among species, suggesting lineage-specific evolutionary trajectories. Phylogenetic analyses showed that individuals from each local population clustered into monophyletic clades, with several unique haplotypes particularly within T. jarbua and A. latus. Overall, the integration of morphological, ecological, and genetic data highlights species-specific adaptations to lagoon habitats and provides valuable insights for monitoring, management, and conservation of fish biodiversity under increasing environmental pressures in central Vietnam.

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DOI: 10.3897/aiep.56.175000

Authors: Wafa Hajlaoui, Sami Mili, Rym Ennouri, Hadil Sessi, Ezzeddine Mahmoudi, Amor Hedfi, Manel Ben Ali, Hechmi Missaoui

Abstract: Effective management of the golden grey mullet, Chelon auratus (Risso, 1810), in Mediterranean coastal ecosystems, including the Bizerte Lagoon, requires a comprehensive understanding of its biological and growth characteristics. This study aimed to assess the biological and growth parameters of Chelon auratus in the Bizerte Lagoon. Sampling was conducted from January to December 2022. A total of 576 specimens, ranging from 15 to 38 cm in length (TL), were caught. Our results indicated that the size at first maturity was 23.46 ± 0.2 cm TL for females and 22.5 ± 0.18 cm TL for males, corresponding to an age of two years. The gonadosomatic index indicated that the spawning season of C. auratus extends from October to December. The mean fecundity of C. auratus was 1233 oocytes per gram of body weight. The total length–weight (W) relationship was estimated at W = 0.0235 × TL2.6875. The monthly percentage of specimens exhibiting a terminal translucent zone indicated that growth rings, or circuli, formed once a year during the cold season in January. The back-calculation method confirmed the effectiveness of using scales to estimate age and growth. Based on the analysis of scales from 576 specimens, the parameters of the von Bertalanffy growth model were estimated as follows: L∞ = 44.25 cm, K = 0.179a–1, t0 = –1.8. A total of six age groups were identified. This study presents the first comprehensive assessment of the reproductive biology, age, and growth of C. auratus in the Bizerte Lagoon, based on year-round sampling. The findings offer valuable insights into the development and reproductive patterns of C. auratus, which will inform the sustainable management of this species in the Bizerte Lagoon.

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DOI: 10.3897/aiep.56.177807

Authors: Yo Su, You-Ci Fan, Yu-Chieh Hsu, Tzu-Yung Lin

Abstract: The beautiful dartfish, Ptereleotris kallista Randall et Suzuki, 2008, is first recorded from Taiwan based on four specimens and a fresh photograph of an additional unretained specimen collected after typhoon events. Previously, this species was known from Luzon, the Philippines and the Milne Bay, Papua New Guinea; therefore, our specimens represent the northernmost record of this species. A detailed description and photographs of the Taiwanese specimens are provided and compared to the type specimens, with observed variations documented and discussed.

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DOI: 10.3897/aiep.56.157532

Authors: Sami Mili, Rym Ennouri, Siwar Agrebi, Manel Fatnassi, Tahani Chargui, Amor Hedfi, Manel Ben Ali, Fehmi Boufahja, Houcine Laouar

Abstract: Despite numerous studies on stocked freshwater fishes in Tunisian reservoirs, the population status of native species remains poorly documented. This study aims to address a critical knowledge gap by assessing the decline in the population of the endemic Algerian barbel, Luciobarbus callensis (Valenciennes, 1842), in Tunisian reservoirs. Standardized fishing operations involving multi-mesh gillnets conducted across 21 reservoirs between 2013 and 2023 revealed that L. callensis was present in only 11 of these reservoirs. This indicates a significant reduction in the species’ range compared to historical records. The species exhibited alarmingly low catch rates (CPUE < 50 fish per 1000 m–2 of nets), except in Bir Mcherga reservoir. The application of data-limited stock assessment methods (CMSY++ and LBB) demonstrates widespread overexploitation across all the reservoirs studied. Length-frequency analysis revealed critical mismanagement: while most of the specimens caught were below the biological maturity threshold, they remain legally exploitable under Tunisia’s outdated minimum size limit. The decline of L. callensis stocks is primarily driven by unsustainable fishing pressure, facilitated by outdated regulations and habitat degradation. These findings highlight the urgent need for a comprehensive conservation management plan to prevent the continued decline of this important native species.

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DOI: 10.3897/aiep.56.184530

Authors: Yuna Dewa, Hiroyuki Motomura

Abstract: A single specimen of Enneapterygius velatus Tashiro, Senou et Motomura, 2018, collected from Iriomote Island, Japan, represents the first record of the species from the Yaeyama Islands. Although considered a deep-water species, the presently reported specimen was collected from the depth of 18 m, on a relatively shallow reef. A detailed description of the specimen and sequence data for the species, based on the mitochondrial COI gene, are provided.

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DOI: 10.3897/aiep.56.173786

Authors: José Carlos Báez, Miguel A. Puerto, Davinia Torreblanca, José L. Varela, Leila Carmona, David Macías

Abstract: This study presents a new record of the white shark, Carcharodon carcharias (Linnaeus, 1758), in Spanish Mediterranean waters. We discuss this finding in the context of documented records from 1862 to 2023, which include direct observations and indirect records such as predation evidence on loggerhead turtles. Together with the present record, these findings support the continued, though infrequent, presence of white sharks in the region. Observations coincide seasonally with Atlantic bluefin tuna migrations, suggesting that prey availability may influence white shark movements.

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DOI: 10.3897/aiep.56.176058

Authors: Christian Vogelmann, Philip Wendt, Andreas Martens

Abstract: On 14 May 2025, three juvenile grass snakes, Natrix natrix (Linnaeus, 1758), were dissected from the stomach of a single rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), caught in the Ammer River, Bavaria, Germany. That record completes the scarce evidence of reptiles as prey in salmonid diets and highlights the trophic plasticity of the introduced O. mykiss.

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DOI: 10.3897/aiep.56.166770

Authors: Cui-Lan Hao, Yu-Lan Ma, Cheng Yue, Yuan-Yuan Yang, Shen-Zhen Xia, Zhi-Heng Li, Yu-Meng Yang, Fang Liu

Abstract: The subfamily Schizopygopsinae (Cyprinidae), endemic to high-altitude Asian ecosystems, is widely used as a model for studying adaptive evolution, owing to specialized hypoxia tolerance and reduced squamation in high-altitude environments. Despite advances in mitochondrial genomics, comprehensive analyses of conserved genomic features and phylogenetic relationships within this subfamily remain limited. Herein, we sequenced and annotated the mitochondrial genome of Diptychus maculatus Steindachner, 1866 (16 764 bp; GenBank: ON872378) and comparatively analyzed the mitogenomes across 56 Cyprinidae species, including 33 Schizopygopsinae members, 21 Schizothoracinae members and two Leuciscinae outgroups (Leuciscus baicalensis, Rutilus rutilus). The mitochondrial genome of D. maculatus exhibited conserved teleost features, including 13 protein-coding genes (PCGs), 22 tRNAs, and 2 rRNAs. Its gene order and strand distribution align with those of related taxa. Notable AT bias (54.3%) and negative GC skew (−0.163) were observed, consistent with mutation-driven thymine accumulation in PCGs. Codon usage analysis revealed a preference for A/T-ending codons, with lineage-specific reductions in relative synonymous codon usage in Diptychus. Phylogenetic reconstructions using Bayesian and maximum likelihood methods resolved Schizopygopsinae and Schizothoracinae into two primary clades, supporting their monophyly but revealing paraphyly in genera Schizothorax and Gymnocypris, which are likely due to rapid radiation and ecological diversification. The placement of D. maculatus as sister to Gymnodiptychus underscores shared adaptations to plateau environments. Our findings highlight conserved mitogenomic architecture shaped by mutation pressure and selection, while phylogenetic discordance with morphology-based classifications emphasizes the need for integrative taxonomic approaches. This study provides critical genomic insights into the evolutionary mechanisms driving high-altitude adaptation and diversification in Schizopygopsinae and offers a foundation for future research on Cyprinidae biogeography and speciation.

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DOI: 10.3897/aiep.56.173510

Authors: John M. Taylor

Abstract: The fall spawning ecotype of the herring, Clupea harengus Linnaeus, 1758, is considered functionally extirpated in the Baltic Proper. Once the dominant ecotype in fisheries landings of herring, few observations of this sub-population have been presented in the 21st century. This short communication describes the opportunistic observation of fall spawning herring larvae in the costal Baltic Proper in 2023 (n = 61) and 2024 (n = 23). Back-calculated hatch dates indicated that the larvae likely hatched between the months of September and December prior to capture. Warmer water temperatures coincided with hatching extending later in the year. This study highlights the presence of a herring ecotype recently considered largely absent from the Baltic Proper and supports the need for further studies to investigate their current role in the ecosystem and herring fishery.

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DOI: 10.3897/aiep.55.174404

Authors: Min-Soo Sohn, Hyuck-Joon Kwun, Jin-Koo Kim

Abstract: A single individual (2318 mm total length) of Strophidon tetraporus Huang et Liao, 2020 was collected from Heuksan-myeon, Sinan-gun, Jeollanam-do, Korea, in December 2023. This species is characterized by the following morphological traits: elongated body, biserial maxillary and dentary teeth, four infraorbital pores, 195 vertebrae (8 predorsal, 79 preanal), and continuous dorsal, anal, and caudal fins. Genetic analysis of the cytochrome oxidase subunit I (COI) sequences confirmed its identity, with only 0.02–0.03 percentage-point divergence from the type specimens of S. tetraporus. This record represents the first verified occurrence of S. tetraporus in Korean waters and extends the species’ distribution to its northernmost limit.

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DOI: 10.3897/aiep.55.173159

Authors: Alan Deidun, Maria Corsini-Foka, Bruno Zava, Alessio Marrone, Giusy Catalano, Valentina Crobe, Fausto Tinti

Abstract: The occurrence of Synodus synodus (Linnaeus, 1758) in the central Mediterranean Sea is ascertained through integrated morphological and molecular analyses conducted on two specimens collected in April 2025 off the southwestern coast of Malta as well as through underwater photographic documentation from the same region. Morphological examination, including meristic counts and morphometric measurements, revealed diagnostic characters consistent with S. synodus, further confirmed by DNA barcoding of the mitochondrial COI gene. The presence of S. synodus in Maltese waters represents the first confirmed record for the area and is added to the sparse reports of the species in the Mediterranean Sea. The occurrence of other Synodontidae recently found in the basin is briefly discussed.

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DOI: 10.3897/aiep.55.168507

Authors: Yoi Ota, Ryuya Sakamoto, Yukiya Ogata, Takumi Kurihara, Atsunobu Murase

Abstract: Zostera japonica Ascherson et Graebner, 1907 is a dominant seagrass species that forms coastal habitats in the northwestern Pacific. Bare areas adjacent to these seagrass beds are also recognized as fish habitat. However, few studies have comparatively evaluated the ecological importance of Z. japonica beds and adjacent bare ground within estuarine environments. We conducted seine net sampling to compare ichthyofaunal composition between Z. japonica beds and adjacent bare ground in a small temperate estuary in Kyushu, southern Japan, during three summer seasons (2015, 2016, and 2019), when seagrass growth is at its peak. Fish species richness and the abundance of the predominant species, Redigobius bikolanus (Herre, 1927), were significantly higher in the seagrass beds than over bare ground. Additionally, the size distribution of R. bikolanus was broader in seagrass beds. PERMANOVA analysis revealed a significant difference in abundance-based species composition between the two habitats, and SIMPER analysis identified three species that contributed most to this distinction: R. bikolanus and Gerres japonicus Bleeker, 1854 (both more abundant in seagrass beds), and Gymnogobius breunigii (Steindachner, 1880) (more abundant over bare ground). These findings imply that Z. japonica beds enhance fish diversity and serve as key habitats for dominant fish species, while adjacent bare ground also supports specific fish communities. The results underscore the importance of conservation efforts within estuaries that account for the ecological roles of both seagrass and bare substrates.

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DOI: 10.3897/aiep.55.171978

Authors: Sanny David P. Lumayno, Ande Bryle N. Genciana, Jezel D. Alcantara, Alan N. Failaman, Victor Marco Emmanuel N. Ferriols, Rex Ferdinand M. Traifalgar

Abstract: The tilapia aquaculture industry faces increasing challenges from saline intrusion into freshwater systems and consumer concerns over hormone-treated fish. This study developed a molecular marker-assisted YY male technology in the saline-tolerant UPV SpiN tilapia hybrid {Oreochromis spilurus (Günther, 1894) × Oreochromis niloticus (Linnaeus, 1758)} to enable all-male progeny production without direct hormone treatment. A primer set (UPV-SpiN-M5) targeting the amhy gene, a key determinant of male sex differentiation, was utilized. Crosses between neofemales (sex-reversed XY females; XY ♀) and natural XY males produced YY supermales, and mating these with natural XX females yielded 100% genotypically male fingerlings all exhibiting the Y-specific band (~523 bp). Despite the limited number of successful spawns among YY supermale × XX female crosses, the successful families produced viable all-male fry, demonstrating the effectiveness of the molecular-assisted approach. These results demonstrate the feasibility of hormone-reduced monosex production in saline-tolerant tilapia and provide a foundation for scalable, sustainable seed production systems suitable for both freshwater and brackish water aquaculture. Future studies should focus on refining broodstock management to improve spawning success, validate genotypic and phenotypic sex at maturity, assess growth and economic performance of YY-derived males, and explore the use of pseudofemales (sex-reversed YY females; YY ♀) to enable the mass production of YY supermales and enhance overall production efficiency.

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DOI: 10.3897/aiep.55.169406

Authors: Armando T. Wakida-Kusunoki, Ivan Oribe-Perez, Vicente Anislado-Tolentino, Luis Fernando Del Moral-Flores, Adrián Enrique Chi Duran

Abstract: This paper reports the first record of leucism in the spotted eagle ray, Aetobatus narinari (Euphrasen, 1790). The specimen was captured on the coast of Seybaplaya, Campeche, on 15 August 2025, using a 20 cm mesh-size gillnet. The disc length and disc width of the leucistic specimen were 376 mm and 656 mm, respectively, and the gutted weight was 3.895 kg. This report contributes to the current knowledge of chromatic abnormalities in elasmobranchs in the southern Gulf of Mexico, which now includes four species. The cause of leucism in this ray remains unknown. Further studies and monitoring are important to identify possible causes of this abnormality, taking into account the health of the specimens and their environmental interactions.

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DOI: 10.3897/aiep.55.170486

Authors: Nader Iskandar Hamwi, Hamam Altajer, Jullanar Salem

Abstract: Between May 2023 and November 2024, 611 specimens of the narrow-barred Spanish mackerel, Scomberomorus commerson (Lacepède, 1800), were collected from artisanal landing sites along the Syrian coast (eastern Mediterranean Sea) to assess stock status in a data-poor fishery. Age was estimated using a multilayer perceptron neural network trained on fork length (FL); the oldest was age 5+ (109.58 cm). Growth conformed to the von Bertalanffy growth function, with K = 0.275 y−1 (95% CI: 0.266–0.284), FL∞ = 127 cm (95% CI: 125.69–128.31). The length–weight relationship indicated negative allometric growth (b = 2.89); and the growth performance index (Φ′) was 3.65, reflecting moderate growth potential. Total mortality (Z) was 1.22 y−1, comprising natural mortality (M) = 0.49 y−1 and fishing mortality (F) = 0.73 y−1, yielding an exploitation rate (E) of 0.60. This exceeds the E0.5 threshold (0.389) for 50% biomass depletion, confirming overfishing. Sensitivity analysis showed E > E0.5 across biologically plausible ranges of FL∞ and K values. A fuzzy logic expert system produced a fishing vulnerability (FV) index of 50.9 and a population growth potential (FP) index of 33.2, indicating high susceptibility to fishing and low recovery capacity. The age structure was severely truncated: only 0.82% reached age 5+, far below the 12–20 years reported in less-exploited populations. We recommend: (i) a minimum landing size of 75 cm FL, (ii) seasonal closures from May to July to protect spawning aggregations, and (iii) enhanced monitoring of artisanal fisheries. Despite uncertainties, integrating artificial neural networks and fuzzy logic offers a robust, transferable approach for stock assessment in data-limited, conflict-affected regions.

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DOI: 10.3897/aiep.55.150774

Authors: Min-Soo Kim, Yu-Sin Shin, Jae-Goo Kim

Abstract: Two specimens, a male–female pair of Favonigobius reichei (Bleeker, 1854) (32.7–41.9 mm SL) were collected from the intertidal zone based on sandy and muddy areas in Jeju-do Island, Korea. This species is distinguished from Favonigobius gymnauchen (Bleeker, 1860), the previously recognized sole representative of the genus Favonigobius in Korea, by the following characteristics: VI–I, 8 dorsal fin rays, I, 8 anal fin rays, predorsal scales 0–1, and the black spot at the base of the caudal fin undivided and rounded. We propose a new Korean common name, “Hwang-jul-nal-gae-mang-duk” for F. reichei based on the yellow stripes on the abdomen of the male.

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DOI: 10.3897/aiep.55.170510

Authors: Tihomir Stefanov, Pencho Pandakov, Nikolay Kodzhabashev

Abstract: Five adult specimens of cactus roach, Rutilus virgo (Heckel, 1852), were collected from the westernmost section of the Bulgarian stretch of the Danube River (rkm 769–844) in April 2025, during the period of spring high waters. This finding constitutes the first confirmed and documented record of the species in Bulgaria. All specimens were in a potential spawning condition, exhibiting mature gonads, and the males displayed well-developed tubercles on the head and front part of the body.

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DOI: 10.3897/aiep.55.163198

Authors: Samira Reinoso, Milton Bohórquez-Cruz, Sandra Rodríguez, Stanislaus Sonnenholzner, Wilfrido Argüello-Guevara

Abstract: This study reports pilot-scale larviculture trials of black snook, Centropomus nigrescens Günther, 1864, a candidate species for aquaculture diversification in the Eastern Tropical Pacific. Fertilized eggs (0.723–0.740 mm diameter) were obtained from spawning induced in broodstock captured from the wild as juveniles and reared in captivity for four years, exhibiting a spherical shape, transparency, buoyancy, and a single oil globule. Two larval culture trials (ER1 and ER2) conducted under hatchery conditions at 24.29 ± 0.13°C and 26.85 ± 0.18°C, respectively, employed a pseudo-green water technique and live feed protocols including enriched rotifers (20–40 ind · mL–1) and Artemia (0.5–4 ind · mL–1). Larvae were initially stocked at 10 larvae L–1 (ER1) and 60 larvae · L–1 (ER2). Growth followed an exponential model, with faster growth rate in ER2. Mean survival rates were 7.42% (ER1) and 6.84% (ER2) at the end of the trials. A total of 17 898 black snook juveniles were produced across both trials (60 and 45 days post hatch, respectively). Cannibalism, parasitic infections (Amyloodinium sp.), and skeletal anomalies were identified as the main bottlenecks affecting survival and juvenile quality. These findings provide preliminary operational insights and represent an initial step towards the development of larviculture protocols for this species.

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DOI: 10.3897/aiep.55.172991

Authors: Hsuan-Ching Ho, Yu-Nung Cheng, Yo Su, Yu-Chieh Hsu, Jeng-Feng Shyu

Abstract: A large specimen of Neoepinnula minetomai Nakayama, Kimura et Endo, 2014 was newly reported from western Taiwan, representing the first record of its range, which extends approximately 1200 km southward from off Kagoshima to western Taiwan. The specimen agrees well with the type series, with the exception of a slightly smaller head and eye. It is suggested that this species may have a broader distribution in the northwestern Pacific Ocean, but is likely to be an insular species. A checklist of all known gempylid fishes from Taiwan is also provided.

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DOI: 10.3897/aiep.55.173888

Authors: Yi Chen Wang, Yu Kai Chen, Ming An Lee

Abstract: Although noncommercial species are generally smaller in body size, they hold considerable ecological value. Because they are often discarded at sea or cannot be collected, basic data on their biological features remain limited. In this study, we explored the length–weight relationships of 17 noncommercial fish species sampled through bottom trawling (16 trawling hauls) in the waters of southwestern Taiwan between 2019 and 2023. Sampling was performed using a bottom trawl with a net opening height of 2.5 m and a width of 30 m; the codend mesh size was 2 × 2 cm. Fork length and body weight measurements were obtained from randomly selected subsamples of the total catch. Twelve species exhibited isometric growth: Ariosoma dolichopterum Karmovskaya, 2015, Crossorhombus kanekonis (Tanaka, 1918), Suezichthys gracilis (Steindachner et Döderlein, 1887), Jaydia truncata (Bleeker, 1855), Lepidotrigla punctipectoralis Fowler, 1938, Ophidion asiro (Jordan et Fowler, 1902), Ostorhinchus kiensis (Jordan et Snyder, 1901), Parapercis sexfasciata (Temminck et Schlegel, 1843), Rogadius asper (Cuvier, 1829), Synodus binotatus Schultz, 1953, Synodus fuscus Tanaka, 1917, and Synodus taiwanensis Chen, Ho et Shao, 2007. Four species exhibited positive allometry—Bleekeria mitsukurii Jordan et Evermann, 1902, Gonorynchus abbreviatus Temminck et Schlegel, 1846, Synodus tectus Cressey, 1981, and Trachinocephalus trachinus (Temminck et Schlegel, 1846), whereas one species exhibited negative allometry—Ratabulus megacephalus (Tanaka, 1917). Overall, this study provides updated insights into the length–weight relationships of data-poor fish species. Our findings may guide studies determining resource status and investigating ecological dynamics in marine ecosystems.

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DOI: 10.3897/aiep.55.160771

Authors: Abdelhamid Helali, Feriel Ghribi, Safa Bejaoui, Manel Ben Ali, Amor Hedfi, Montaser Hassan, Wafa Hajlaoui, Dalya Belhassen, Imene Chetoui, Rym Ennouri, Siwar Agrebi, Sami Mili

Abstract: This study provides a comprehensive analysis of the annual biological cycle and biochemical composition of the bluemouth rockfish, Helicolenus dactylopterus (Delaroche, 1809), collected in 2022, from the northern Tunisian coast. We investigated seasonal variations in biological indices (condition, gonadosomatic, and relative growth) and biochemical constituents (lipids, proteins, glycogen, and fatty acids). Our key finding is a defined cold-season (winter) spawning period, evidenced by a significant peak in the gonadosomatic index (GSI) coinciding with a depletion of somatic condition, hepatic glycogen, and lipid reserves. Spawning was associated with a pronounced shift in energy allocation, with lipid and glycogen levels in muscle tissue decreasing by up to 92% and 88%, respectively, in winter. Biochemically, the species exhibited high protein content (41–77 mg · g–1) and was rich in omega-3 fatty acids, particularly in warm seasons (PUFA n-3 = 28%). The fatty acid profile (FA) was dominated by PUFA > MUFA > SFA year-round, with notable differences in energy reserves between sexes, as females showed higher energy mobilization for reproduction. These results provide crucial insights into the reproductive biology and energy allocation strategy of H. dactylopterus, underscoring its vulnerability to fishing pressure during spawning and its consistent nutritional value, which is vital for sustainable management in the Mediterranean.

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DOI: 10.3897/aiep.55.168427

Authors: Reo Koreeda, Ying Giat Seah, Md Repin Izarenah, Hiroyuki Motomura

Abstract: Myersina yangii (Chen, 1960), previously recorded from Taiwan (type locality), the Philippines, Indonesia, Thailand, and India, is recorded from Malaysia for the first time, a single male specimen having been collected from the Malacca Strait, off Perak, western Peninsular Malaysia. Although recent studies have regarded a transverse black band on the mid-lateral body as a diagnostic feature of the species, the original description of M. yangii ascribed that character only to females. Accordingly, M. yangii, considered extinct in Taiwan, although recently collected (in 2019) and reported as an unidentified species of Myersina, is here recognized as extant in that region. Two male specimens, collected from Malaysia and Taiwan, enabled descriptions of the fresh color pattern of the species for the first time, together with several minor intraspecific variations: 10 anal-fin soft rays (usually 11) and a single black blotch on the first dorsal-fin fourth or fifth spine (at least in males). The likelihood of a small-scale patch on the chest (when undamaged) was noted in the Taiwan specimen.

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DOI: 10.3897/aiep.55.158826

Authors: Serkan Saygun, Murat Gündoğan

Abstract: In this study, the chromosome numbers and karyotypes of two marine fish species, representing two families, living off the south coast of the Black Sea were successfully determined using the short-term culture method (PB-MAX™ application). Although the culture incubation periods, depending on postmortem timing, are non-identical for each species, the kidney tissues of the fish samples were treated in Falcon tubes filled with PB-MAX™ for 3–4 h. Subsequently, hypotonic and fixation procedures were applied consecutively, and then spreading was done by dropping the cell suspension onto steamed, clean slides. Giemsa staining, C-banding, and Ag-NOR banding were applied to the preparations. We determined that the Mediterranean horse mackerel, Trachurus mediterraneus (Steindachner, 1868), 2n = 48, has 6 metacentric, 16 submetacentric, 18 subtelocentric, and 6 acrocentric chromosomes (NF–70); while the black scorpionfish, Scorpaena porcus Linnaeus, 1758, 2n = 42, has 4 metacentric, 4 submetacentric, 10 subtelocentric, and 24 telocentric chromosomes (NF–50). Trachurus mediterraneus represents the family Carangidae, while Scorpaena porcus belongs to the family Scorpaenidae. In conclusion, while the number and location of NOR and C+ chromosomes in both species differed from previous studies, in the presently reported study we also observed similarities in the 2n counts. The differences in karyotypes were also observed, in comparison to other studies. This study, using image analysis software, updated information on the chromosomal structures of both species. Thus, the in vitro method used has proven to eliminate the problem of failing to obtain high-quality chromosomes in marine fish, making it undeniably the most efficient and economical short-term culture method. Furthermore, it can be predicted that enabling the exposure of chromosomes from even post-mortem fish samples will provide advantages and time savings, as well as facilitate the easy, rapid, and high-quality chromosomes required for further molecular cytogenetic studies. This study aims to pave the way for chromosome research on sea fish to be conducted in a shorter timeframe with practical approaches. It also seeks to revise the karyotypes of the two marine fish revealed by this short-term cell culture.

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DOI: 10.3897/aiep.55.166777

Authors: Hyuck Joon Kwun

Abstract: A single specimen of Neoclinus (family Chaenopsidae) was collected from the East Sea, Korea, in June 2016.This is the first report of the larval stage of Neoclinus chihiroe Fukao, 1987. The lack of distinctive morphological features in fish larvae makes species identification difficult; however, the species was identified through DNA barcoding. Analysis of mitochondrial DNA cytochrome oxidase subunit I revealed that the larval specimen corresponds to an adult of N. chihiroe reported from Korea in 2021. Morphologically, the larval specimen of N. chihiroe is characterized by the posterior tip of the maxilla being located below the middle of the eye, two multifid cirri on the orbit, dorsal fin with 13 spines and 15 soft rays, anal fin with 2 spines and 27 soft rays, and 13 pectoral fin rays. In the pigmentation pattern, there are three pairs of melanophores on the top of the head (one pair in each of the interorbital, occipital, and nape regions), several melanophores in a row from the isthmus to the anus, six pale melanophores on both sides of the dorsal contour, and many melanophores along the ventral contour on the anal fin base.

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DOI: 10.3897/aiep.55.164833

Authors: Yun Jeong Cho, Jong-Wook Kim, Cheol-Woo Park, Soo In Lee, Jae-Goo Kim

Abstract: Invasive alien fish species, such as the largemouth bass, Micropterus salmoides (Lacepède, 1802), and bluegill, Lepomis macrochirus Rafinesque, 1819, have rapidly spread across freshwater ecosystems in Korea, raising serious ecological threats. This study investigated the impact of these invasive alien species on fish communities in large lakes and small reservoirs over a 5-year monitoring period (2019–2023). Eight sites, including four lakes and four reservoirs, were surveyed twice a year. Fish were collected using cast nets, kick nets, and gillnets (for lakes). Species diversity indices (Shannon’s Hʹ, Pielou’s Jʹ, and Margalef richness) and dominance indices were calculated. Poisson-based analysis of variance models was applied to examine the relationship between the densities of invasive alien species and the diversity of fish communities. Sites with higher densities of largemouth bass and bluegill had significantly lower diversity indices. Non-metric multidimensional scaling analyses indicated distinct community groupings according to the type of waterbody and the presence of invasive alien species. These results emphasize the need for continued monitoring and management strategies tailored to different habitat scales.

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DOI: 10.3897/aiep.55.163641

Authors: Vytautas Rakauskas, Andrius Steponėnas, Tomas Virbickas, Jacek Wolnicki

Abstract: The endangered lake minnow, Rhynchocypris percnurus (Pallas, 1814), has been known from Lithuanian inland waters for over 20 years, but we have a very limited understanding of its current population size. The main purpose of this study was to provide a concise account of the species in Lithuania, including a rough assessment of threats to its populations and habitats. In 2018–2019, we investigated 360 small water bodies across the country, all of which were potentially suitable for lake minnows. Results revealed that lake minnows were present in only 12 water bodies, all concentrated in one regional park in the southern part of the country. However, by 2024 the species had gone extinct at nine of these sites due to habitat loss. At present (2025), only one viable Lithuanian population of this species can be considered to exist. Our results conclusively show that the species is on the very edge of extinction. Urgent action is needed to protect this species in Lithuanian waters, with special emphasis on revitalizing its most suitable habitats and translocating fish from the only currently known population in Lithuania.

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DOI: 10.3897/aiep.55.164842

Authors: Edmond Hala, Marco Kule, Elvis Kamberi, Rigers Bakiu, Janek Simon

Abstract: The European eel, Anguilla anguilla (Linnaeus, 1758), is a critically endangered species with a complex life cycle affected by many environmental factors. Its high flexibility in several biological parameters emphasizes the need for regional management strategies. To support management and population modeling, a study was conducted on the age, growth, and other biological characteristics of eels in a coastal lagoon—this being the first study of its kind conducted in the southwest of the Adriatic Sea for the European eel to date. A total of 435 silver eels were collected from commercial catches in the Karavasta Lagoon, Albania, at the start of their migratory journey from 2022 to 2024. The length–weight relationships revealed distinct growth patterns for both males (b = 2.8) and females (b = 2.7), indicating negative allometric growth. The ages of silver eels ranged from 4 to 11 years, with males averaging 6.2 years and females 7.0 years, the latter being significantly older. Throughout their lives in the lagoon, females also exhibited a higher mean annual growth in length (6.4 cm) compared to males (5.7 cm). Swim bladders of all eels were free from infection with Anguillicola crassus, a common and widespread nematode parasite. These results offer important insights into eel population dynamics in transitional waters and form the basis for conservation efforts in Adriatic Sea ecosystems. These data are vital for creating sustainable management strategies, mainly due to the decline in eel populations.

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DOI: 10.3897/aiep.55.167883

Authors: Mustafa Tolga Tolon, Serhat Engin, Adnan Tokaç

Abstract: The length–weight relationship (LWR), condition factor (K), and biometric characteristics (body wall, viscera, and gonads) of the commercially important sea cucumber, Holothuria tubulosa Gmelin, 1791, from the northeastern Aegean Sea in Türkiye were analyzed based on 327 individuals collected monthly from October 2018 to September 2019. The total length (TL), wet weight (WW), gutted weight (BW), viscera weight (VW), and gonad weight (GW) were determined for each sea cucumber to the nearest 0.1 cm for length and 0.01 g for weight. The sex of each individual was identified through macroscopic observation of gonad coloration, facilitating the categorization of biometric relationships according to sex. Results revealed negative allometric growth (b = 1.458) for H. tubulosa, with length increasing more than weight. The allometric growth values, calculated as 1.208 in males and 1.584 in females, did not differ significantly between the sexes. The mean condition factor was 2.42 ± 1.04, displaying significant seasonal patterns, with peaks in February and October and the lowest values during summer. Notably, smaller individuals (<100 g) exhibited significantly higher K values, suggesting better health. A strong positive linear relationship was observed between wet and gutted weights (R2 = 0.549). Body composition analyses revealed a declining proportion of gutted weight with increasing total wet weight, whereas the relative proportions of viscera, gonads, and water content were positively correlated with body size. These findings offer region- and species-specific insights that can enhance the accuracy of stock assessments and support adaptive management strategies for the H. tubulosa fishery.

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DOI: 10.3897/aiep.55.163128

Authors: Si-Won Choi, Se Hun Myoung, Chang-Soo Bae, Min-Su Woo, Yun-Bae Kim, Joo Myun Park

Abstract: Valenciennea wardii (Playfair in Playfair et Günther, 1867) often exhibits color variations depending on its habitat. However, owing to its reclusive behavior and low abundance, it is challenging to collect V. wardii using fishing gear, and ecological and population genetic studies remain limited. On 11 November 2024, a single specimen of the tropical gobiid fish V. wardii, which was previously unrecorded in the waters around the Korean Peninsula, was collected from the coastal waters off Ulleung Island via SCUBA diving. It was analyzed using detailed morphometric and meristic measurements in conjunction with mitochondrial cytochrome c oxidase subunit I (COI) sequencing to confirm its taxonomic identity. Morphological analysis revealed distinct characteristics, particularly brown transverse body bands and a black blotch with a white margin on the first dorsal fin, which distinguish it from other closely related species. Genetic analysis showed high similarity to V. wardii specimens collected from the South China Sea and Sri Lanka but indicated notable divergence from those collected in the Philippines, suggestive of potential cryptic diversity within the species. This study reports the poleward range expansion of V. wardii and proposes the new Korean name “gal-saeg-tti-bok-gi-mang-duk” based on the characteristics of this species having dark brown transverse bands. These records provide concrete evidence for the poleward expansion of this tropical marine fish species and play a crucial role in monitoring the impacts of climate change on marine ecosystems.

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DOI: 10.3897/aiep.55.161420

Authors: Chris Jan P. Dinaga, Ande Bryle N. Genciana, Alan A. Failaman, Maria Alexandra G. Fontanilla, Regie A. Estrada, Emelyn Joy G. Mameloco, Victor Marco Emmanuel N. Ferriols, Rex Ferdinand M. Traifalgar, Sanny David P. Lumayno

Abstract: Application of feminization techniques using estrogen hormones can be relevant in cases where there is an insufficient supply of female stock for broodstock production. This study aimed to evaluate the feminization efficiency (FE) of 17β-estradiol (E2) at various concentrations using two different methods applied to the saline-tolerant SpiN (Oreochromis spilurus × O. niloticus) tilapia hybrid developed by the University of the Philippines Visayas (UPV). E2 concentrations of 0, 50, 100, and 200 mg · kg–1 were orally administered through dietary supplementation for 28 days (d) to one batch after yolk-sac absorption. Another batch, still with yolk-sacs, was immersed in E2 solutions at concentrations of 0, 50, 100, 200, and 400 µg · L–1 for 5 d. Soft dorsal fin tissues from phenotypically identified female tilapia were collected upon sexual maturation and processed for DNA extraction, PCR, and gel electrophoresis to determine the genotype. Selective removal of the first six dorsal spines was conducted to generate up to 63 unique codes for temporary fish identification. Treatments 2 (50 mg · kg–1) and 3 (100 mg · kg–1) resulted in the highest FE for dietary supplementation at 94.74% and 95.24%, respectively, while feminization through larval immersion was observed only in Treatment 3 (100 µg L−1) at an efficiency of 16.67%. Neither feminization method significantly affected the survival of the fish. These results demonstrate that dietary supplementation with 50–100 mg · kg–1 of E2 is an effective and reliable method for feminizing UPV SpiN tilapia hybrid. PCR-based genotyping confirmed the conversion of genetic males (XY) into phenotypic females. This approach offers a practical strategy to enhance broodstock management, particularly in the development of all-female stocks for breeding. Future studies should focus on evaluating the growth and reproductive performance of sex-reversed individuals for long-term broodstock viability.

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DOI: 10.3897/aiep.55.163321

Authors: Alan Deidun, Maria Corsini-Foka, Bruno Zava, Alessio Marrone, Giusy Catalano, Fausto Tinti

Abstract: The occurrence of Synodus synodus (Linnaeus, 1758) in the central Mediterranean Sea is ascertained through integrated morphological and molecular analyses conducted on two specimens collected in April 2025 off the southwestern coast of Malta as well as through underwater photographic documentation from the same region. Morphological examination, including meristic counts and morphometric measurements, revealed diagnostic characters consistent with S. synodus. DNA barcoding of the mitochondrial COI gene further supported this identification, with BOLD assigning the sequences to a S. synodus with 99.84% similarity. The presence of S. synodus in Maltese waters represents the first confirmed record for the area and is added to the sparse reports of the species in the Mediterranean Sea. The occurrence of other Synodontidae recently found in the basin is briefly discussed.

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DOI: 10.3897/aiep.55.164723

Authors: Ryusei Furuhashi, Ying Giat Seah, Hiroyuki Motomura

Abstract: A single specimen (128.3 mm standard length) of Saurida fortis Furuhashi, Russell et Motomura, 2022, previously recorded only from Japan, Taiwan and the Gulf of Thailand, was recently collected off Johor, east coast of Peninsular Malaysia. Described in detail, the specimen represents the first record of S. fortis from Malaysia, being the southernmost record of the species. However, records of S. fortis from the Gulf of Thailand were excluded from the distribution of that species, the specimens being possibly misidentified as S. micropectoralis.

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DOI: 10.3897/aiep.55.156936

Authors: Wafa Hajlaoui, Sami Mili, Ezzeddine Mahmoudi, Dalya Belhassen, Amor Hedfi, Manel Ben Ali, Hechemi Missaoui

Abstract: Mugil cephalus Linnaeus, 1758 and Chelon ramada (Risso, 1810) are the most commonly caught species of the family Mugilidae in Tunisian dam reservoirs. Efforts are underway to boost production to meet domestic demand. We investigated the biological and growth parameters of Mugil cephalus and Chelon ramada based on catches in the Sidi Saad Reservoir. Our results showed that the lengths at first maturity were 34.13 ± 0.12 cm for females M. cephalus and 33.29 ± 0.15 cm for males. For C. ramada, the corresponding sizes at first maturity were 30.5 ± 0.22 cm for females and 29.4 ± 0.17 cm for males. The gonadosomatic index indicated that the spawning season for M. cephalus extends from August to October, while that of C. ramada occurs from October to December. Notably, M. cephalus reaches sexual maturity at a larger size compared to C. ramada. We also assessed the von Bertalanffy growth parameters for both species: L∞ = 77.87 cm, K = 0.1147 a–1, t0 = –2.41 for M. cephalus, and L∞ = 52.01 cm, K = 0.1782 a –1, t0 = –1.41 for C. ramada. Our findings provide essential insights into the reproductive biology and growth parameters of these two Mugilidae species. However, more detailed surveys are necessary to manage fish resources sustainably in Tunisian dams.

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DOI: 10.3897/aiep.55.156837

Authors: Heber Zea-de la Cruz, César Meiners-Mandujano, Javier Tovar-Ávila, Lourdes Jiménez-Badillo, Jorge Luis Oviedo-Pérez

Abstract: The length–weight relationships (LWR) of eleven demersal elasmobranch species captured in the southern Gulf of Mexico were estimated and assessed to provide previously absent somatometric conversion factors. A total of 8852 specimens representing eight families and eleven species caught as bycatch in the Mexican shrimp trawl fishery were analyzed. The following species were covered: Hypanus americanus (Hildebrand et Schroeder, 1928); Gymnura lessae Yokota et Carvalho, 2017; Narcine bancroftii (Griffith et Smith, 1834); Dipturus olseni (Bigelow et Schroeder, 1951); Rostroraja texana (Chandler, 1921); Pseudobatos lentiginosus (Garman, 1880); Rhinoptera bonasus (Mitchill, 1815); Sphyrna tiburo (Linnaeus, 1758); Squatina dumeril Lesueur, 1818; Mustelus canis (Mitchill, 1815); Mustelus norrisi Springer, 1939. The values of the allometric growth parameter b ranged from 2.5 to 3.2, consistent with the expected range. The somatometric growth exhibited negative allometry in fifteen estimations, isometry in six, and positive allometry in two. The LWR differed by sex in five of the six species examined under this criterion, with females consistently exhibiting greater size and weight than males. This study provides the first published LWR for Narcine bancroftii, Dipturus olseni, Rostroraja texana, and Pseudobatos lentiginosus, along with novel LWR estimates for Hypanus americanus, Gymnura lessae, Rhinoptera bonasus, Squatina dumeril, and Mustelus canis in the Gulf of Mexico. It also presents new maximum lengths for R. texana and P. lentiginosus.

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DOI: 10.3897/aiep.55.151044

Authors: Nelson Colihueque, Francisco Estay

Abstract: The flank skin spot patterns for identification of rainbow trout individuals may be useful as an alternative non-invasive tagging method for addressing biological questions related to this species, including issues relevant to fish farming. This approach has potential because the spot arrangement is usually specific to each individual. In this study, we analyzed the flank spot patterns of individuals from two rainbow trout Oncorhynchus mykiss (Walbaum, 1792) populations—one naturalized population (n = 56, Calafquén Lake, Región de La Araucanía) and one farmed population (n = 45, Piscícola Huililco Ltd., Región de La Araucanía)—to evaluate whether these spot patterns are useful for the photo-identification of fish. The flanks of the individuals were photographed with a digital camera. Then, the spot pattern of each image was annotated with freely available software (Interactive Individual Identification System, I3S) to evaluate the performance of these patterns in identifying individuals based on a ranking image score where each image was compared with all annotated images stored in an identification database. Spot patterns for long-term identification were also evaluated using a subset of images from the farmed population. The use of spot patterns showed a high performance for the identification of individuals, because in both populations, all annotated images ranked the first ranking score, indicating perfect recognition. The long-term analysis revealed a high performance in recognition of individuals because 75% of the images of fish at the age of 2 years were successfully matched with images of the same fish at the age of 3 years.

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DOI: 10.3897/aiep.55.151390

Authors: Armando T. Wakida-Kusunoki, Luis Fernando Del Moral-Flores, Eduardo García-Mercado, Joshep Heredy Galindo-Hernández

Abstract: Armored catfishes of the genus Pterygoplichthys are naturally distributed in South America, two of their species are exotic and invasive in Mexico and have been widely reported, especially in the southeast. In this work, we report for the first time the presence of Pterygoplichthys pardalis (Castelnau, 1855) in the Noh, Chama, and Chan Laguna hydrological system. A specimen of P. pardalis was captured in the Chan Laguna area on 9 December 2024. Further research is needed to understand the dispersal pathways of this type of fish, as well as its potential effects on native fish populations and local fisheries implications.

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DOI: 10.3897/aiep.55.156276

Authors: Harutaka Hata, Lauren Sallan, Hsuan-Ching Ho

Abstract: Three specimens of the Hasselt’s rainbow sardine Dussumieria hasseltii Bleeker, 1851, collected from southwestern Taiwan, were discovered in the fish collection of National Museum of Marine Biology and Aquarium, Taiwan. Due to the previous taxonomic confusion, records of species belonging to this genus from Taiwanese waters are mostly ambiguous, and only two species, Dussumieria acuta Valenciennes, 1847 and Dussumieria modakandai Singh, Jayakumar, Kumar, Murali, Mishra, Singh et Lal, 2021, have been confirmed recently. The presently reported specimens represent the first records of D. hasseltii based on voucher-specimens from Taiwanese waters, as well as the northernmost record in the western Pacific Ocean. Detailed description and comment on the Taiwanese records are provided.

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DOI: 10.3897/aiep.55.155497

Authors: Teena T. K. Jayakumar, Ronald Fricke, T. T. Ajith Kumar, Uttam Kumar Sarkar

Abstract: The blackedge cusk, Ophidion muraenolepis Günther, 1880, is recorded from the Laccadive Sea based on four specimens collected at Sakthikulangra landing center, Kollam, Kerala. Morphometric and meristic data for the species are given and compared to the congeners. This represents the first record of this species from the Laccadive Sea, western Indian Ocean, documenting the range extension of the species.

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DOI: 10.3897/aiep.55.148612

Authors: Zdeněk Adámek, Luděk Šlapanský, Pavel Jurajda

Abstract: The rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), is a popular species for Czech recreational fishing, both on trout fishing grounds and even some designated as non-trout waters if they have sufficient environmental quality. Rainbow trout are usually stocked using a “put-and-take” management approach, in which the majority of fish are caught and harvested during the fishing season. Rainbow trout stocking and return data in anglers’ catches were analyzed with respect to the time period between stocking and catch and the rates of return were evaluated. Two differently managed types of fishing grounds were taken into account—the non-trout and trout grounds. The study was conducted on five fishing grounds (four rivers) in the Czech Republic within 2007–2020. The average proportion of stocked rainbow trout caught during the first two weeks after release on non-trout fishing ground is 92.3%, significantly (P < 0.001) higher than the 64.1% taken from designated trout grounds. On the trout fishing grounds, rainbow trout tend to be caught more evenly throughout the fishing season. Mean total individual return rates ranged between 36.8% and 53.4% in the non-trout fishing ground and between 29.8% and 68.4% in the trout fishing ground. The respective weight return rates were 47.7%–79.5% in the non-trout fishing ground and 34.4%–75.3% in the trout fishing ground with no significant differences in individual (P = 0.50) and weight-related (P = 0.19) returns. The vast majority of rainbow trout are caught and harvested shortly after being stocked. The proportion of stocked fish caught within two weeks of release in non-trout fishing grounds is significantly higher than in trout grounds. Stocked rainbow trout tend to be caught more evenly throughout the fishing season in trout fishing grounds due to lower angling pressure and legal restrictions (artificial flies and lures only). Both individual and weight returns for the entire year (season) were similar in non-trout and trout areas.

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DOI: 10.3897/aiep.55.148496

Authors: Mahadurage I. G. Rathnasuriya, Thennakoon H. I. S. Hapuarachchi

Abstract: Oarfishes, representing the family Regalecidae, are poorly known from the tropical Indian Ocean and are of exceptional interest in terms of their distribution. This study presents the first detailed morphological description of Regalecus russellii (Cuvier, 1816) based on the single specimen (2580 mm total length) collected from Sri Lankan waters on 27 October 2021. The morphological characters of the presently reported specimen well matched the key identification features of R. russellii reported from the eastern and western Pacific Ocean, and the Atlantic Ocean. This report of R. russellii from the Indian Ocean provides vital information on their biology and distribution.

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DOI: 10.3897/aiep.55.133988

Authors: Mary Jessa Bell B. Pagapulan, Rex Ferdinand M. Traifalgar, Sanny David P. Lumayno, Fredson H. Huervana, Dennis K. Gomez

Abstract: The Pacific white shrimp, Penaeus vannamei Boone, 1931, is one of the valuable globally-cultured species. However, its production in the Philippines has declined due to disease outbreaks. One essential approach to improve shrimp production is the use of domesticated broodstock to produce pathogen-free larvae, combined with well-formulated maturation diets, although fresh feeds can pose risks like disease transmission and water quality issues. Golden apple snail foot tissue meal (GASFTM) presents a cost-effective alternative protein source to squid meal, offering high protein content and the potential to improve aquaculture feed formulations. A 32-day feeding trial evaluated the effects of GASFTM on ovarian maturation of P. vannamei female broodstocks. Five isonitrogenous and isolipidic experimental diets containing increasing levels of GASFTM: control (0%), T1 (25%), T2 (50%), T3 (75%), and T4 (100%) were formulated. Polychaetes/squids and a basal control diet were used as the positive and negative controls, respectively. Each treatment with triplicate groups of 15 unilaterally eyestalk-ablated shrimp female broodstocks at early stages of ovarian development was fed with test diets. The ovarian development was tracked every four days. The results showed that the maximum ovary shadow ratios (OSR) as a measure of ovarian size was not different among the treatments. Ovarian maturation time (OMT) defined as the period between the initial and maximum OSR development indicate that the test diets with 50%, 75%, and 100% GASFTM were significantly shorter than those of the other treatments. The study also indicated that the test diets with 75% and 100% GASFTM inclusion were the most effective on P. vannamei ovarian maturation, followed by the test diet with 50% GASFTM inclusion. These findings suggest that GASFTM is a viable protein source for enhancing ovarian maturation and reproductive performance in P. vannamei broodstock.

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DOI: 10.3897/aiep.55.151622

Authors: Alejandro Padilla-Sánchez, Sara E. Domínguez-Cisneros, Ernesto Velázquez-Velázquez, Abraham Kobelkowsky

Abstract: The genus Tlaloc contains four valid species and forms part of the family Profundulidae, a group of small freshwater fishes endemic to the Mesoamerican region. The objective of this study was to provide a detailed description of the urohyal bone of two species of Tlaloc—Tlaloc labialis (Günther, 1866) and T. candalarius (Hubbs, 1924)—and to evaluate the usefulness of this osteological structure in delimiting these taxa. The urohyal bone is a single bony structure located in the ventral part of the head in both species and is the result of ossification of an unpaired tendon of the sternohyoideus muscle. Data from cleared and double-stained museum specimens of the focal taxa were analyzed, including morphometric measurements of each urohyal bone taken using an ocular micrometer connected to a stereomicroscope. We found the most notable difference between the two species was the height of the urohyal neck, which was significantly narrower in T. candalarius (6.66%–11.11% of total urohyal length) than in T. labialis (13.15%–25%) based on the non-parametric Mann–Whitney U test. Our results show that measuring the urohyal bone offers a reliable and attractive alternative for taxonomic determination of Tlaloc labialis vs. T. candalarius due to the operational simplicity and speed of such measures. Our work also highlights the utility of more detailed osteological analyses in taxonomic and systematic studies of profundulids.

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DOI: 10.3897/aiep.55.151025

Authors: Yo Su, Jian-Fu Huang, Fan-Yi Yang

Abstract: The Japanese lanternfish, Notoscopelus japonicus (Tanaka, 1908), is for the first time recorded from Taiwan based on four specimens. This species has previously been known from temperate waters of the North and Central Pacific Ocean, therefore our specimens represent the southernmost record of this species. Fresh photographs and a detailed description are provided. Currently, 60 species in 17 genera of myctophids are known from Taiwanese waters, including three species representing Notoscopelus. A checklist of myctophids of Taiwan is provided and discussed.

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DOI: 10.3897/aiep.55.147223

Authors: Luis Fernando Del Moral-Flores, Sergio Alejandro Lozano-Quiroz, Viridiana R. Escartín-Alpizar, Eduardo García-Mercado, Rolando Hernández-Ortiz

Abstract: We report an adult male bluntnose sixgill shark, Hexanchus griseus (Bonnaterre, 1788), of 326 cm in total length and 197 kg, which was captured by longline at a depth of about 120 m off Veracruz, Mexico. It was characterized by having six gills, six rows of large, serrated comb-shaped teeth on each side of the lower jaw. This record is the first for the southern Gulf of Mexico and the first confirmed for Mexican waters of the Gulf of Mexico and the Caribbean Sea.

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DOI: 10.3897/aiep.55.149577

Authors: Rizalyn M. Picoy-Gonzales, Nathaniel C. Añasco, Joy C. Lizada, Kazuhiko Anraku, Harold M. Monteclaro

Abstract: This study investigated the capture performance of two types of Philippine crab pots, a dome-type (DCP) and a box-type (BCP) installed with a pair of laboratory-tested escape gaps with flap through actual fishing operations. A total of 30 units of DCP and 30 units of BCP, of which 15 were gapped and 15 were conventional, were deployed in each fishing trial. Over the sampling period, 12 fishing trials were conducted resulting in a total of 180 hauls per pot type per design. The results showed the potential of 48 × 25 mm escape gaps with flaps in improving the selectivity and efficiency of crab pot gears used in catching blue swimming crab Portunus pelagicus (Linnaeus, 1758). The gapped crab pots significantly reduced the catch of undersized P. pelagicus by 48% in DCP and by 79% in BCP. The non-target catch was also reduced in the gapped pots by 67% in DCP and 72% in BCP. In addition, the capture of legal-sized P. pelagicus was not affected by the presence of the escape gaps in both DCP and BCP. Further, catch species richness was reduced in gapped DCP. The catch retrieval and sorting time was also reduced in both gapped DCP and BCP.

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DOI: 10.3897/aiep.55.145362

Authors: Yaqiu Liu, Chendong He, Mingdian Liu, Weitiao Chen, Yuguo Xia, Yuefei Li, Shuli Zhu, Jie Li, Xinhui Li

Abstract: The length–weight (LWR) and length–length (LLR) relations of 23 species of native freshwater fishes of six families and three orders collected from the Yuanjiang River in the upper reaches of the Red River were analyzed. From June 2023 to October 2024, specimens representing 23 freshwater fish were obtained: Cyprinus rubrofuscus Lacepède, 1803; Placocheilus caudofasciatus (Pellegrin et Chevey, 1936); Poropuntius krempfi (Pellegrin et Chevey, 1934); Microphysogobio yunnanensis (Yao et Yang, 1977); Abbottina rivularis (Basilewsky, 1855); Opsariichthys bidens Günther, 1873; Hemibarbus medius Yue, 1995; Onychostoma gerlachi (Peters, 1881); Rasbora atridorsalis Kottelat et Chu, 1988; Schistura macrotaenia (Yang, 1990); Schistura fasciolata (Nichols et Pope, 1927); Vanmanenia tetraloba (Mai, 1978); Beaufortia leveretti (Nichols et Pope, 1927); Sinogastromyzon tonkinensis Pellegrin et Chevey, 1935; Bagarius rutilus Ng et Kottelat, 2000; Glyptothorax quadriocellatus (Mai, 1978); Glyptothorax honghensis Li, 1984; Glyptothorax interspinalum (Mai, 1978); Hemibagrus pluriradiatus (Vaillant, 1892); Pseudobagrus kyphus Mai, 1978;Tachysurus fulvidraco (Richardson, 1846); Tachysurus virgatus (Oshima, 1926); and Channa gachua (Hamilton, 1822). The total length (TL), standard length (SL), and body weight (BW) were determined for each fish individual to the nearest 0.1 cm and 0.1 g, respectively. All LLR and LWR parameters of 23 fish species were statistically significant (P < 0.001). The length–weight relations of 17 species have not previously been available in FishBase. Moreover, we provided a new distribution record of fish (Rasbora atridorsalis). Our study provided LWR values for the first time, which will help validate the accuracy and predictability of Bayesian models in estimating species-specific growth parameters for data-poor species. The majority of the LWR relations obtained in this study are new to this region. The availability of species- and region-specific data on length–weight relations could help inform future research and management of these species.

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DOI: 10.3897/aiep.55.146367

Authors: Yo Su, Yu-Nung Cheng, Jeng-Feng Shyu

Abstract: The Hureau’s flounder, Engyprosopon hureaui Quéro et Golani, 1990 is first recorded from Taiwan based on a female specimen and fresh photographs of an unretained specimen. Even though it has been recorded from sparse localities in the Indo–West Pacific, it has never been recorded from Taiwan. The presently reported specimen fills the distribution gap in the northwestern Pacific Ocean between Japan and New Caledonia. A detailed description of the specimen is provided and compared to data of other specimens, with morphological variations noted. Additionally, a revised key to the 12 species of Engyprosopon from Taiwan is provided.

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DOI: 10.3897/aiep.55.143930

Authors: Min-Soo Kim, Kyu-Jin Kim, Min-Ho Jang, Jae-Goo Kim

Abstract: A single specimen of Lutjanus xanthopinnis Iwatsuki, Tanaka et Allen, 2015 (78.9 mm standard length), was collected from Hahyo Port in Jeju-do Island, Korea. The specimen is characterized by X, 13 dorsal fin rays, III, 8 anal fin rays, 16 pectoral fin rays, 49 lateral line scales, 5 scale rows on cheek, scales on preopercular flange, posterior nostril shape oviform, predorsal scales reaching anteriorly approximately the midpoint of the interorbital area. A new Korean name, “No-rang-tung-dom” is proposed based on the presence of several thin yellow horizontal stripes below the lateral line on the body.

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DOI: 10.3897/aiep.55.139721

Authors: Roxanne Cabebe-Barnuevo, Dianne Frances Penuela, Emmanuel S. Delloro Jr., Ricardo P. Babaran, Hiroyuki Motomura, Maria Celia D. Malay

Abstract: This annotated checklist documents the diversity of cartilaginous fishes, including sharks, batoids (rays and skates), and chimaeras, from Panay and Guimaras islands, Western Visayas, Philippines, through surveys at fish markets and ports. A total of fourteen species were sampled and identified, including one chimaera, six sharks, and seven batoids from ten families (Chimaeridae, Hemiscylliidae, Scyliorhinidae, Carcharhinidae, Pristiophoridae, Rhinobatidae, Plesiobatidae, Urolophidae, Dasyatidae, and Aetobatidae). Among these, the presence of the sandbar shark, Carcharhinus plumbeus (Nardo, 1827) in Philippine waters is confirmed for the first time, whereas a potential unidentified batoid species within the genera Himantura Müller et Henle, 1837 and Urolophus Müller et Henle, 1837 are reported. The twelve nominal taxa described herein include three species classified as Least Concern, five are Near Threatened, two Vulnerable, one Endangered, and one is Critically Endangered as per the IUCN Red List assessments. These documented species supplement recent inventories, expanding our knowledge on the diversity and distribution of cartilaginous fishes in the region and country, while also providing comprehensive morphological descriptions, validated molecular data, and curated voucher specimens for future reference.

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DOI: 10.3897/aiep.55.146945

Authors: Neven Iveša, Moira Buršić, Jakov Dulčić

Abstract: This study reports the first capture of Lagocephalus sceleratus in the northern Adriatic, specifically in Medulin Bay at a depth of 19.7 m. The specimen, a 522 mm male weighing 1330 g, was caught on 13 May 2024. This is the fourth record in the Adriatic and the northernmost one for both the Adriatic and Mediterranean seas. Stomach analysis revealed bivalves, gastropods, sea urchin fragments, and inorganic particles. The further spread of this tetraodontid species in the Adriatic poses ecological and socio-economic risks, such as disruptions to fisheries, biodiversity loss, and threats to marine ecosystems. Effective management requires monitoring, regulation, public education, and citizen science involvement.

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DOI: 10.3897/aiep.55.140634

Authors: Huy Xuan Chu, Toan Quang Le, Ngoc Minh Nguyen, Ai Huyen Thi Tong, Huy Quang Bui, Hai Hoang, Hai Phuc Nguyen, Hieu Duc Nguyen, Anh Ngoc Thi Do

Abstract: The distribution of larvae and juveniles of Ayu, Plecoglossus altivelis (Temminck et Schlegel, 1846), is shaped by intricate interplays involving environmental variables and anthropogenic influences. The intricate interplay and equilibrium among these factors will govern the distribution and abundance of Ayu fish larvae and juveniles in estuarine settings. In this investigation, a hybrid Ant Colony Optimization-Adaptive Neuro-Fuzzy Inference System (ACO-ANFIS) model was utilized to enhance the precision of Ayu fish larvae and juvenile’s occurrence estimation for the period from 2021 to 2022. The outcomes evinced that the hybrid model displays strong predictive capabilities, with R2test > 0.75, and AUC > 0.79. Among the environmental parameters, temperature, salinity, and turbidity exhibit the highest correlations with Ayu fish occurrence, with R values of 0.47, 0.54, and 0.40 for the Ka Long estuary, and 0.49, 0.50, and 0.42 for the Ba Lat estuary, respectively. The presence of Ayu species is limited to northern Vietnam, albeit with a declining pattern from the Ka Long estuary to the Ba Lat estuary. The study’s outcomes propose that the identification of suitable habitats and the cartography of fish distribution are invaluable for scrutinizing the ramifications of natural and anthropogenic influences on species distribution.

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DOI: 10.3897/aiep.55.144960

Authors: Jesús Genaro Sánchez-Martínez, Isidro Otoniel Montelongo-Alfaro, Jaime Luis Rábago-Castro, Roberto Pérez-Castañeda, María De La Luz Vázquez-Sauceda, Flaviano Benavides-González, Jorge Loredo-Osti

Abstract: Ligictaluridus floridanus (Mueller, 1936) is a monogenean parasite that affects farmed channel catfish, Ictalurus punctatus (Rafinesque, 1818). No studies, however, have been conducted on this monogenean’s infection dynamics. The aim of this study was to determine the prevalence and mean abundance of L. floridanus on channel catfish fry in a cohabitation experiment. The experiment was performed in triplicate and involved the introduction of five infected fish to a 40-L aquarium that contained 30 naive fish. The trial lasted 29 days and was conducted in a system with a continuous water flow. The percentage of naive fish that were infected increased sharply, from 0% to 100%, between the second and third days after cohabitation. On the subsequent days of the experiment, 100% prevalence was observed, except for days 23 and 26, when it was 66%. The dynamics of infection with L. floridanus showed its main peak five days after cohabitation, exhibiting a dome-shaped function. The left side of the fitted function represented the abrupt increase in parasite abundance in a few days, while the right side depicted its gradual decrease. One would expect that when L. floridanus enters the catfish culture system, it will be able to infect all fish (100% prevalence) within a few days. This would occur primarily in floating cage culture systems, where fish density is usually high. The parasite can disperse rapidly throughout all the gill arches when its abundance exceeds a certain threshold. Further studies on the reproductive patterns of this parasite and the factors affecting its variability are necessary to have a better understanding of its host dynamics and life cycle parameters.

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DOI: 10.3897/aiep.55.138745

Authors: Prihatiningsih Prihatiningsih, Tirtadanu Tirtadanu, Muhammad Taufik, Rosmiati Rosmiati, Erfind Nurdin, Anthony Sisco Panggabean, Duranta Diandria Kembaren, Nurulludin Nurulludin, Umi Chodrijah, Ralph Thomas Mahulette, Budi Nugraha

Abstract: The southern Java waters are characterized by a strong upwelling process, making the region a potential hotspot for fishing activities, including the largehead hairtail, Trichiurus lepturus Linnaeus, 1758. This study provides data on various aspects of T. lepturus in the southern Java waters, including reproductive biology, growth parameters, mortality rates, spawning potential ratio (SPR), and yield per recruit (Y/R). The results are intended to help sustain the management of T. lepturus fisheries in the southern Java waters. A total of 19 587 fish specimens were collected monthly between January 2019 and December 2021 from fishermen’s catches in the southern Java waters at the Palabuhanratu Archipelago Fishing Port, West Java Province, Indonesia. The data collected involved information on length, weight, sex, and gonads. Length-frequency data were analyzed using various fisheries assessment models. A length–weight relationship follows a positive allometric growth pattern. The sex ratio was slightly female-biased. Gonadal maturity stages (GMS) and the gonadosomatic index (GSI) indicated a prolonged spawning period. The length at first maturity (Lm50) males and females was estimated at 84.5 cm and 77.0 cm, respectively. The von Bertalanffy growth equation of T. lepturus in southern Java waters is Lt = 131.67(1 – e–0.22(t + 0.5094)). Total mortality (Z), natural mortality (M), and fishing mortality (F) were 1.60 year−1, 0.44 year−1, and 1.16 year−1, respectively. The spawning potential ratio (SPR) was 26%, and the yield per recruit (Y/R) analysis suggested that the current fishing effort is above the maximum sustainable yield level. Trichiurus lepturus in southern Java waters is experiencing high fishing pressure, which may compromise its reproductive potential and long-term sustainability. Management measures should be implemented to regulate the fishing effort and ensure the sustainable exploitation of this vital fishery resource.

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DOI: 10.3897/aiep.55.143882

Authors: Alan Deidun, Maria Corsini-Foka, Alessio Marrone, Gianni Insacco, Jean Paul Schembri, Arnold Sciberras, Mario Santoro, Flavia Occhibove, Antonio Di Natale, Bruno Zava

Abstract: The wahoo, Acanthocybium solandri (Cuvier, 1832), an uncommon scombrid species for the Mediterranean, is hereby reported for the first time from Maltese waters. Details of this unusual capture, and characteristics of the specimens recovered are provided, as well as a brief discussion on dynamics of its introduction in the Mediterranean Sea, and its distribution in this area. In addition, two individuals of the parasitic nematode Anisakis pegreffii Campana-Rouget et Biocca, 1955 (Anisakidae) were found from the stomach of one of the specimens.

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DOI: 10.3897/aiep.55.142574

Authors: Kunto Wibowo, Teguh Peristiwady, Petrus Makatipu, Selvia Oktaviyani, Dian Oktaviani, Gema Wahyudewantoro

Abstract: This study reports the first equatorial records of four demersal marine fish species, Plectranthias yamakawai Yoshino, 1972, Aulacocephalus temminckii Bleeker, 1855, Iniistius geisha (Araga et Yoshino, 1986), and Randallichthys filamentosus (Fourmanoir, 1970), collected off Lembeh Island, northern Sulawesi, Indonesia. All these species had been previously reported only from higher latitudes in the Northern and Southern Hemispheres, leading to their classification as anti-equatorial. Their presence in equatorial Indonesian waters at 1.4°N latitude suggests that their distributions extend beyond those usually regarded as anti-equatorial and that a re-evaluation of their biogeographical classification would be in order. In particular, the need for further research on deep-sea fish diversity in extremely low latitude regions is highlighted.

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DOI: 10.3897/aiep.54.132489

Authors: Aye Aye Min, Toe Toe Soe, Thida Lay Thwe, Pwint Thu Aye, Than Than Lwin, Ye Win Thaung, Tint Lwin, Aung Naing Oo, Wai Lin Maung, Khin Maung Maw, Shota Hosono, Hiroyuki Matsui, Shota Mitsui, Takeshi Terahara, Masato Endo, Masashi Yokota, Takeshi Kobayashi

Abstract: The silond catfish, Silonia silondia (Hamilton, 1822), known locally as Nga Myin Yinn, is rare in Myanmar fish markets and can fetch a high price. Efforts are being made to increase the production for domestic demand. We examined the distribution and growth of S. silondia based on catches in the Ayeyarwady River and growth records in fish farms near the river. The smaller fish were observed downstream near their nursery and the medium fish were around 1 m total length (TL) were often widespread, whereas the larger fish preferred upstream locations. Estimating the individual age from poorly defined periodic rings on the surface of otolith sections was difficult, but their microchemistry may reflect a shared nursery environment and subsequent migration throughout the entire river region. The growth curve estimates in the farmed population revealed a mean TL of 60 cm at four years, indicating that farmed fish were smaller than commercially captured wild fish. This is one of the first comprehensive studies of the river region, but more detailed surveys are needed to manage the fish resource sustainably.

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DOI: 10.3897/aiep.54.131982

Authors: Rizza Mae Guyapale, Cleresa Dionela, Fredson Huervana

Abstract: One of the major challenges in an intensive recirculating aquaculture system (RAS) is the sustainable management of fish sludge. The sludge contains a significant amount of nutrients that can be utilized by hydroponically grown crops in an integrated system called aquaponics. While this system has promising results, techniques to maximize nutrient recovery still need to be developed. African catfish, Clarias gariepinus (Burchell, 1822), can be stocked at very high densities, therefore it produces a substantial amount of sludge. In this study, sludge from African catfish RAS was subjected to different mineralization treatments (T1: anaerobic, T2: aerobic, and T3: aerobic with carbon addition) for nutrient recovery. The supernatant in T3 after mineralization had a statistically significant difference (P > 0.05) in their concentrations of N (2700 mg ∙ L–1), P (100 mg ∙ L–1), K (720 mg ∙ L–1), Ca (12 115.6 mg ∙ L–1), and Mg (3391.9 mg ∙ L–1) after 15 days, among the other mineralization methods and untreated sludge. It was then followed by the nutrient recovery performance of T2 and lastly, T1. Moreover, the low pH and warm temperature were observed to improve the solubilization of the nutrients, resulting in a higher nutrient recovery in T3. Hence, among the three mineralization treatments, T3 had the most potential to recover maximum nutrients from African catfish sludge to be used as organic fertilizer for hydroponically grown crops.

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DOI: 10.3897/aiep.54.138051

Authors: Armando T. Wakida-Kusunoki, Vicente Anislado-Tolentino, Luis Fernando Del Moral-Flores, Rodolfo Castro-Barbosa

Abstract: The first case of xanthochromism in a female common snook, Centropomus undecimalis (Bloch, 1792), in the southern Gulf of Mexico is described. The specimen supporting this record was caught off the coast of Tabasco, Mexico and it represents the first fish case of this abnormal coloration in the Gulf of Mexico. The analyzed specimen measured 774 mm in total length. Its body was entirely orange with a lighter shade of orange on the belly, while the normal coloration of this fish species is dark to opaque grey with yellow to green tints on the dorsal part, silvery lateral side, white belly, and black lateral line. It is uncertain what caused this abnormality, but it is hypothesized that multiple environmental stressors, natural and anthropogenic, were responsible for the appearance of this particular abnormality and other similar cases in the area. Additional sampling and long-term monitoring are needed to determine the possible causes and their ecological impacts.

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DOI: 10.3897/aiep.54.135133

Authors: Huy Quang Nguyen, Huong Thi Thanh Dang, Thuy Thi Ta, Chi Linh Do, Hau Duc Tran

Abstract: The length–weight relationships (LWRs) of 11 fish species from one national park and three nature reserves, in northern Vietnam, totaling 737 individuals between October 2018 and November 2021, are described in this study. The following species, representing 11 genera and seven families, were studied: Aphyocypris normalis Nichols et Pope, 1927, Barbodes semifasciolatus (Günther, 1868), Beaufortia pingi (Fang, 1930), Carassius auratus (Linnaeus, 1758), Glyptothorax honghensis Li, 1984, Hemibarbus medius Yue, 1995, Macropodus opercularis (Linnaeus, 1758), Neolissochilus benasi (Pellegrin et Chevey, 1936), Onychostoma gerlachi (Peters, 1881), Opsariichthys minutus Nichols, 1926, Rhinogobius duospilus (Herre, 1935). All regressions were highly significant (P < 0.001). Positive allometric growth was seen in six species (b > 3, P < 0.01) and isometric growth in five species (b = 3, P > 0.05). This is the first report on the LWRs of six fish species, including Beaufortia pingi, Barbodes semifasciolatus, Neolissochilus benasi, Opsariichthys minutus, Glyptothorax honghensis, and Rhinogobius duospilus from four conservation areas. The presently reported study provides foundational data for future stock assessment works and management initiatives in protected areas, as well as facilities comparisons of LWRs from different habitats.

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DOI: 10.3897/aiep.54.135448

Authors: Yuna Dewa, Hiroyuki Motomura

Abstract: Presently reported single specimen of Enneapterygius rhothion Fricke, 1997, previously considered endemic to waters off New Caledonia and Vanuatu, represents the first record from Australia and the northernmost record of the species. In addition, Enneapterygius olivaceus Dewa, Tashiro, et Motomura, 2023, originally described from Japan and the Philippines, is also newly recorded from Australia and Vanuatu, being the first record of the species from the Southern Hemisphere.

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DOI: 10.3897/aiep.54.134294

Authors: Maribel Badillo Alemán, Ariana Solís Gómez, Alfredo Gallardo Torres, Eduardo Pacheco Gongora, Xavier Chiappa-Carrara

Abstract: The Otolith Collection of Fishes from the Gulf of Mexico and Caribbean Sea was created with the objective to conserve and illustrate the diversity of these structures from species living in the Gulf of Mexico, the Caribbean Sea, and the freshwater and brackish systems of the Yucatan Peninsula, incorporating morphological descriptions and morphometric data. Otoliths, non-skeletal calcareous structures that develop in the inner ear of fish, are essential for balance and hearing. They have become pivotal tools for age and growth determination, population analysis, and ecological, trophic, and archaeological studies due to their resistance to degradation and the extensive information they provide about the environment and physiology of fish. The collection now includes otoliths from 214 species, representing 67 families, obtained through sampling campaigns and collaborations with local fishermen. The otoliths are extracted using techniques that ensure the integrity of the structures for later preservation. High-resolution images were obtained using optical and scanning electron microscopy, and these images are stored in an online database. This database facilitates research and teaching by providing public access to digital specimens and associated data. In addition to fostering academic development, this collection represents a significant step towards the creation of a national platform for otolith data analysis, aligned with international efforts to digitize biological collections. Despite the financial and logistical challenges involved in building and maintaining biological collections, this collection demonstrates its value as an essential resource for taxonomic, systematic, and ecological studies, as well as for biodiversity education and awareness. The online availability of the collection not only facilitates access to data but also promotes innovation and international collaboration in the study of fishes and their habitats.

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DOI: 10.3897/aiep.54.134405

Authors: Shintaro Hashimoto, Reo Koreeda, Md Repin Izarenah, Ying Giat Seah, Hiroyuki Motomura

Abstract: A single specimen collected off Perak, Malaysia was identified as Priacanthus blochii Bleeker, 1853, being characterized by 13 dorsal-fin soft rays, 14 anal-fin soft rays, the dorsal and anal fins relatively low and rounded distally, 21 total gill rakers on the first arch, 77 scales in lateral series, the 10th dorsal-fin spine 1.59 times the length of the second dorsal-fin spine, the pectoral-fin length 48.0% of the head length, the posterior margin of the caudal fin convex, a black blotch absent anteriorly on the dorsal-fin membrane, and a single large black blotch on the pelvic-fin base. In Southeast Asian waters, P. blochii has been recorded to date, from Thailand (Andaman Sea), the Philippines, and Indonesia. A previous Malaysian record, based on a photograph purported to be of P. blochii, was identified here as Priacanthus sagittarius Starnes, 1988, the specimen reported here being the first record of P. blochii from Malaysia.

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DOI: 10.3897/aiep.54.130966

Authors: Peimin Yu, Zhengli Luo, Liangming Wang, Yan Liu, Yingbang Huang, Binbin Shan, Changping Yang, Dianrong Sun

Abstract: The well-being of marine ecosystems significantly influences biodiversity and ecological equilibrium amidst pressing challenges such as overfishing, water pollution, and climate change. Drawing upon data from two fishery stock surveys conducted in the inshore waters of Hainan Island in 2022, this study undertook a comprehensive evaluation of the marine ecosystem’s health status in the region. Employing the Fish Index of Biological Integrity (F-IBI) analysis method, coupled with an examination of the structural and functional aspects of the fish community, our research sheds light on the prevailing conditions. Our study revealed a spatial dichotomy within the fish communities of the study area and delineated them into two distinct groups: the northwestern and southeastern ones, with evident disparities in community structure between the two. By employing indicator screening and calculation, we segmented the fish health index in the inshore waters of Hainan Island into five tiers. Despite discernible anthropogenic influences, the ecological health of these waters remained generally robust. Notably, the mean F-IBI of fall (56.30) significantly exceeded that of spring (48.16) (P < 0.01). Furthermore, regarding spatial distribution, the ecological well-being of the southeastern waters surpassed that of the northwestern and Qionghzhou Strait waters. This study represents a pioneer endeavor to apply ecological health assessment methodologies towards informing resource management and conservation strategies for the inshore fisheries of Hainan Island. By furnishing a scientific foundation, our research contributes to the pursuit of sustainable marine ecological development within this locale.

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DOI: 10.3897/aiep.54.122366

Authors: Sébastien Lavoué, Jamsari Amirul Firdaus Jamaluddin, Abdullah Halim Muhammad-Rasul, Mohd Lokman Ilham-Norhakim, Khaironizam Md Zain

Abstract: The phylogenetic position of the Southeast Asian catfish genus Encheloclarias Myers, 1937 within the family Clariidae is inferred herein using three mitochondrial nucleotide markers: cytochrome b, cytochrome oxidase subunit I, and 16S rRNA genes. We found that Encheloclarias is neither exclusively related to the African taxa having extended neural spines posterior to the dorsal fin (Encheloclarias shares with some of these taxa the presence of an adipose fin, as opposed to absent in all other clariid taxa) nor to the Asian species of the genus Clarias Scopoli, 1777. Encheloclarias is hypothesized to be the sister group of all other clariids, except Horaglanis Menon, 1951. The inferred position of Encheloclarias confirms that the adipose fin in this genus has an evolutionary origin independent to that of the adipose fin found in some African clariids. Encheloclarias is not only ecologically remarkable, being adapted to acidic peat swamps in Southeast Asia, but it is also an ancient lineage sheltering in these habitats. However, the precise timing of the colonization of peat swamps by Encheloclarias remains to be investigated. The phylogenetic position of Encheloclarias further underscores the importance of studying and protecting the remaining peat swamp habitats in Southeast Asia and their distinctive aquatic fauna.

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DOI: 10.3897/aiep.54.126623

Authors: Justin C. Bagley, Maria Florencia Breitman

Abstract: Here, we use long-term monitoring data from fisheries surveys across six Mississippi River reaches spanning > 750 river miles (>1200 km) to estimate length–weight relationships (LWRs) for 14 cypriniform fishes native to the Upper Mississippi River system. Relationships between log10-transformed values of fish total weights [g] and total lengths [cm] were analyzed using standard linear modeling and hypothesis-testing approaches. Focal species included four North American minnows in family Leuciscidae [Cyprinella lutrensis (Baird et Girard, 1853), Notropis atherinoides Rafinesque, 1818, Notropis hudsonius (Clinton, 1824), and Paranotropis volucellus (Cope, 1865)] and 10 suckers in the family Catostomidae [Carpiodes carpio (Rafinesque, 1820), Carpiodes cyprinus (Lesueur, 1817), Carpiodes velifer (Rafinesque, 1820), Cycleptus elongatus (Lesueur, 1817), Ictiobus bubalus (Rafinesque, 1818), Ictiobus niger (Rafinesque, 1819), Moxostoma anisurum (Rafinesque, 1820), Moxostoma carinatum (Cope, 1870), Moxostoma erythrurum (Rafinesque, 1818), and Moxostoma macrolepidotum (Lesueur, 1817)]. Congruent with previous studies, estimates of parameter b were consistent with isometric or weakly allometric growth and ranged from 2.834 (P. volucellus) to 3.351 (C. elongatus), while estimates of parameter a ranged from 0.002 (C. elongatus) to 0.014 (C. velifer).

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DOI: 10.3897/aiep.54.122733

Authors: Hsuan-Ching Ho, Quang Van Vo

Abstract: A large individual of Meadia roseni Mok, Lee et Chang, 1991 is reported from central Vietnam for the first time, which also represents the first record outside the type locality, Taiwan. Herein we document the expansion of the distribution of this species, along with a detailed description and fresh color photos. The new finding may suggest that M. roseni has a broader distribution but somewhat restricted in the northern South China Sea.

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