Effect of different levels of dietary copper nanoparticles and copper sulfate on growth performance, blood biochemical profiles, antioxidant status and immune response of red sea bream (Pagrus major)

• Effects of dietary nanocopper (Cu-NPs) or copper sulfate (CuSO4) on red sea bream were investigated.
• Fish that were fed with 2 mg Cu-NPs kg− 1 displayed improved growth performance.
• Fish that were fed with Cu-NPs diets, showed higher antioxidant defense system.
• Fish that were fed with Cu-NPs diets, showed higher immune response.
• Supplementation of Cu-NPs was much effective than CuSO4 on red sea bream performances.

A 60 days feeding trial was conducted to evaluate the effects of dietary copper nanoparticles (Cu-NPs) or copper sulfate (CuSO4) on growth performance, blood biochemical profiles, antioxidant status and immune response of red sea bream (Pagrus major) (initial body weight: 3.30 ± 0.02 g). Six diets were formulated containing CuSO4 or 2, 4, 6 or 8 mg supplemental Cu as NPs were supplied to the basal diet (control). The obtained results showed that, fish fed diets supplemented with Cu-NPs at levels of 2 and 4 mg kg− 1 had the highest values of final body weight, weight gain, specific growth rate, feed intake, protein gain and tolerance against low-salinity stress. Significantly higher feed efficiency ratio, protein efficiency ratio, protein retention, whole body Cu content, protease activity, lysozyme activity and total serum protein were found at levels of 2 mg Cu-NPs kg− 1 diet when compared with the control group. Whole body protein of fish fed diet Cu-free diet was significantly lower than those of fish fed other diets. Fish fed diets supplemented with Cu-NPs at different levels gave the lowest values of plasma glucose. Furthermore, fish fed diets supplemented with Cu-NPs at 2 and 4 mg kg− 1 diet were in better conditions whereas, fish fed control diet implied comparatively higher oxidative conditions. Therefore, the data of the present study recommend adding 2 mg Cu-NPs per kg diet to improve fish growth, immune response and antioxidant defense system.Statement of relevanceEfficiency of copper for red sea bream.