The aim of this study was to assess the effects of different doses of selenium nanoparticles (nano-Se) on growth performance, feed conversion, tissue composition, Se accumulation in muscle and liver, antioxidant response and biochemical blood parameters of common carp, Cyprinus carpio. Nano-Se was added to the experimental basal diets at the rates of 0 (control), 0.5, 1 and 2 mg/kg dry feed weight. Four groups of fish with an average weight of about 10 g were fed one of the experimental diets for 8 weeks. Fish that were fed diet supplemented with 1 mg Se/kg displayed improved (P < 0.05) growth performance, including final weight and weight gain (WG). No significant differences (P > 0.05) in feed conversion ratio (FCR) and survival were observed in fish fed different diets for 8 weeks. Dietary nano-Se had no effects on proximate composition of carps. Fish fed with nanoselenium-supplemented diets showed a higher (P < 0.05) Se content in the muscle and liver tissues compared to that of the control. Liver malondialdehyde (MDA) level was significantly (P < 0.05) lowered in fish fed on diet supplemented with 2 mg nano-Se/kg, whereas the activity of glutathione peroxidase (GPx) and catalase (CAT) in livers of carp fed on diet supplemented with 2 mg nano-Se was significantly (P < 0.05) higher as compared to other experimental diets. The highest superoxide dismutase (SOD) activity was observed in fish fed on 2 mg nano-Se, but it was not significantly (P > 0.05) different from the enzyme activity in the 1 mg nano-Se group. Fish fed on diet supplemented with 2 mg nano-Se showed significantly (P < 0.05) higher total protein and globulin contents but lower albumin level. The serum cholesterol level was significantly (P < 0.05) decreased in fish fed diets containing 2 mg nano-Se/kg. No significant difference (P > 0.05) in serum triglycerides was observed in fish fed different diets. A significant (P < 0.05) decrease in low-density lipoprotein (LDL) was observed in groups receivin
