The aim of present study was to determine the LC50/96 h value of copper sulfate and determine the growth performance of Caspian Sea kutum) Rutilus frisii kutum (fingerlings during 60-days sub-lethal copper (Cu). After acclimation period to two weeks, for determine the LC50/96 h value, total of 27 aquarium with a capacity of 60 L each stocked with 10 fishes an aquarium. Tunney four aquarium and 8 concentrations of (Cu) composed the 24 treatments while 3 other aquaria were used as control. For each treatment, three replications were conducted. And experiment to determine the growth performance fish were transferred into fiberglass aquaria of 200 L water capacity for growth trials. The treated fish were kept in the aquarium containing sub-lethal concentrations of Cu (0.11 and 0.23 mg L-1) and affected to grow for 60 days, while control fish were placed in metal free water. The results indicated that median lethal concentrations (LC50) of copper to Caspian Sea kutum for 96 h exposure was 2.310 ppm. The chronic sub-lethal water-borne Cu exposure to the fish exerted that fish had significantly decreased final body weight in comparison to control group. The copper sulfate also had significant negative effects on specific growth rate (SGR) and feed conversion efficiency (FCE) in comparison to those fed the control group. The feed conversion ratio (FCR) and condition factor (CF) were significantly increased in comparison with the control group (P < 0.05). Also survival rate in experimental treatments in comparison with control group, was significantly decreased (P < 0.05). The treated fish exhibited significantly lower body weight and length gains than that of control. The increments of fish weights, fork and total lengths, condition factor, feed intake and condition factor of treated and control fish varied significantly during study period. Hence, concluded that copper sulfate is toxic for Caspian sea kutum (Rutilus frisii kutum).