The aim of this study was to evaluate the effects of dietary diphenyl diselenide [(PhSe)2] at different concentrations (1.5, 3.0, and 5.0 mg/kg) on growth, oxidative damage and antioxidant parameters in silver catfish after 30 and 60 days. Fish fed with 5.0 mg/kg of (PhSe)2 experienced a significant decrease in weight, length, and condition factor after 30 days and these parameters increased after 60 days. Thiobarbituric acid reactive substances (TBARS) and protein carbonyl (PC) decreased in the liver of silver catfish supplemented with (PhSe)2 after 30 days at all concentrations, while after 60 days these parameters decreased in liver, gills, brain, and muscle. Supplementation with (PhSe)2 induced a decrease in catalase (CAT) activity from liver only after 60 days of feeding. Superoxide dismutase (SOD) decreased at 5.0 mg/kg after 30 and 60 days and glutathione peroxidase (GPx) was enhanced at 1.5 and 3.0 mg/kg after 30 and 60 days. Silver catfish supplemented for 30 days showed a significant increase in liver glutathione S-transferase (GST) at 3.0 mg/kg, while after 60 days GST activity increased in liver at 1.5, 3.0, and 5.0 mg/kg and in gills at 3.0 and 5.0 mg/kg of (PhSe)2. After 30 days, non-protein thiols (NPSH) did not change, while after 60 days NPSH increased in liver, gills, brain, and muscle. In addition, ascorbic acid (AA) levels after 30 days increased in liver at three concentrations and in gills and muscle at 1.5 mg/kg, while after 60 days, AA increased at all concentrations in all and tissues tested. Thus, diet supplemented with (PhSe)2 for 60 days could be more effective for silver catfish. Although the concentration of 5.0 mg/kg showed decreased growth parameters, concentrations of 1.5 and 3.0 mg/kg, in general, decreased oxidative damage and increased antioxidant defenses.
Keywords: Antioxidants; Fish; Oxidative parameters; Selenium.