Effects of dietary Cu nanoparticles on growth performance, physiology and bioaccumulation in Asian walking catfish (Clarias batrachus)

The present investigation was conducted to determine the optimal dietary Cu-NPs requirement of Asian walking catfish, Clarias batrachus (7.46 ± 0.15 cm; 5.28 ± 0.10 g) by feeding with diets supplemented with different concentrations of Cu-NPs (10, 20, 30, 40 and 50 mg/kg) and control group. Each experimental diet was hand-fed to triplicate groups of fish for 60 days in glass aquarium. Results showed that fish group fed with 20 mg/kg Cu-NPs in feed exhibited highest (P < 0.05) growth performance and feed utilization compared to the control group. However, increased level of Cu-NPs from 30 to 50 mg/kg in feed significantly reduced the growth performance. Significantly higher protein and lipid were also recorded at 20 mg/kg Cu-NPs supplemented group. Haematological parameters, serum lipid and enzymatic profile were found to influence significantly with the addition of Cu-NPs in feed compared to the control group. Based on the polynomial regression analysis between FW, WG and SGRW against dietary Cu-NPs levels, the optimal dietary supplementation of Cu-NPs for C. batrachus were estimated to be ranged between 19.98 to 20.05 mg/kg per diet, respectively. Bioaccumulation of Cu was the highest in liver compared to muscle and serum, whereas the highest Cu accumulation was observed at 50 mg/kg Cu-NPs supplemented group. The findings of the present study will be helpful for formulating nutrient rich low cost catfish feed.