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This study aimed to determine the optimal dietary copper requirement for juvenile bighead carp ( Aristichthys nobilis ). Six diets were formulated by supplementing a basal diet with 2.49, 5.15, 7.99, 14.11, 25.75 and 49.21 mg/kg copper from CuSO₄·5H₂O. 900 Juvenile bighead carp (initial weight: 1.40±0.04 g) were fed these diets for 67 days to analyze growth performance, body composition, tissue copper accumulation, serum biochemical indices, and digestive enzyme. Weight gain rate (WGR) and specific growth rate (SGR) peaked at 1356.98% and 3.98% day-1 in the 14.11 mg/kg copper group, significantly exceeding the control group (P intestinal wall > vertebrae > gill > muscle. Dietary copper improved hepatic function, evidenced by reduced serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), alongside enhanced calcium and phosphorus metabolism. The addition of dietary copper inhibited the activities of intestinal amylase and lipase. The results demonstrated that dietary copper levels of 7.99–25.75 mg/kg significantly improved liver function, enhanced serum calcium and phosphorus, and promoted erythropoiesis, hematocrit, and hemoglobin synthesis. Broken-line regression analysis identified the optimal copper requirement as 12.13–12.23 mg/kg for maximal WGR and SGR. These findings provide a practical basis for copper supplementation in bighead carp aquaculture.
Ji et al. (Mon,) studied this question.