Background. Oxidative stress poses a serious threat to farmed fish, exemplified by depressed growth, decreased disease resistance, and reduced flesh quality. Therefore, the aim of this study was to examine differences in activity of antioxidant enzymes and concentration of selected biochemical parameters between blood plasma of both sexes of three species important for sustainable development of aquaculture: tench, Tinca tinca (Linnaeus, 1758); wels catfish, Silurus glanis Linnaeus, 1758; and sterlet, Acipenser ruthenus Linnaeus, 1758. Materials and methods. Experimental fishes were fed ad libitum for 60 days with a formulated diet (45% proteins, 20% fat, 16% carbohydrates, 8% ash and 2% fibre). At the end of the study venous blood samples were collected and 11 biochemical parameters were assessed: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), total antioxidant capacity (FRAP), alanine transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), bilirubin, albumin, and uric acid. Results. Comparison between species revealed that the most significant differences were observed for tench and sterlet (in FRAP, GPx, CAT, GST LDH, ALT, bilirubin, and uric acid), less significant—for sterlet and wels (in FRAP, GST, LDH, AST, bilirubin, uric acid), followed by tench and wels catfish (in FRAP, GPx, GST, AST, and uric acid). Moreover, significant variations in the level of biochemical markers were also detected between sexes within each species, where the highest number was observed for tench (in FRAP, GPx, albumin, and uric acid), next wells catfish (in SOD, albumin, and bilirubin), and the lowest in sterlet (in ALA). Additionally, numerous differences in antioxidant potential (FRAP), antioxidant defence indices, as well as in markers of liver function, heart dysfunction, and markers of nutritional status were observed as species-specific and sex-specific. Conclusion. Results obtained in this study for the first time demonstrated species- and sex-related differences in plasma activity of antioxidant enzymes and concentration of selected biochemical parameters between tench, wels catfish, and sterlet reared in cage culture. The presented findings provide significant contribution not only to the existing knowledge of fish physiology but will also help to design optimal feeding practices to achieve sustainable cage aquaculture.

antioxidative enzymes, oxidative stress, Polish aquaculture, reactive oxygen species, sturgeon