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.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.55.161420

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.55.151044

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.53.113220

Authors: Olga Revina, Vjačeslavs Revins, Dina Cīrule, Anda Valdovska

Abstract: The presently reported study intended to examine the effect of the oral administration of an immunomodulator β-glucan and β-glucan-containing product (BGN-2) on the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), fish heat shock protein 70 (HSP-70), and fish growth hormone (GH) as well as growth performance of cultured sea trout juveniles. The sea trout is a migratory sea-run brown trout, Salmo trutta Linnaeus, 1758. The fish (total of 15 000) were divided into four experimental and one control group including control (consisting of basal diet) (D1); basal diet + 1 g kg–1 β-glucan (D2); basal diet + 3 g kg–1 β-glucan (D3); basal diet + 6 g kg–1 BGN-2 (D4); basal diet + 14 g kg–1 BGN-2 (D5). The fish fed D4 and D5 diets showed significantly higher IL-6, HSP-70, and GH expression levels than other treatments (P < 0.05). Sea trout fed D4 and D5 diets showed significant improvements in growth performance compared to the fish fed the control diet. In conclusion, our results suggest that dietary supplementation with the product BGN-2 provides great immunostimulation and could be used as an effective measure to improve growth performance in juvenile sea trout.

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