Evaluation of Toxicity of Dietary Chelated Copper in Juvenile Olive Flounder, <i>Paralichthys olivaceus,</i> Based on Growth and Tissue Copper Concentration

Abstract

The present study was conducted to determine the safe and toxic levels of dietary copper in juvenile olive flounder, Paralichthys olivaceus, fed Mintrex ® copper, a chelated dietary copper source. Fish averaging 3.8 ± 0.13 g (mean ± SD) were fed 1 of 10 diets ( n = 3) containing 7 (Cu 0 ), 10.4 (CuM 5 ), 15.8 (CuM 10 ), 24.9 (CuM 20 ), 43.4 (CuM 40 ), 82.1 (CuM 80 ), 158 (CuM 160 ), 308 (CuM 320 ), 658 (CuM 640 ), and 1267 (CuM 1280 ) mg Cu/kg diet. At the end of 12 wk of feeding trial, weight gain (WG), specific growth rate, and protein efficiency ratio of fish fed CuM 5 and CuM 10 diets were significantly higher than those fed CuM 80 , CuM 160 , CuM 320 , CuM 640 , and CuM 1280 diets ( P &lt; 0.05). Survival of fish fed Cu 0 , CuM 5 , CuM 10 , CuM 20 , and CuM 40 diets was significantly higher than those of fish fed CuM 320 , CuM 640 , and CuM 1280 diets. Whole‐body lipid content of fish decreased while whole‐body ash increased with dietary copper levels. Whole‐body and tissue copper concentrations increased with dietary copper levels. Although ANOVA test suggested that the toxic level of dietary Cu in juvenile olive flounder, P. olivaceus , could be 320 mg/kg diet, broken‐line analysis of WG indicated a level of 286 mg/kg diet when Mintrex ® Cu is used as the dietary copper source.