Abstract
Heavy metals can threaten ecosystem health and of food security. The purpose of percent study was evaluating the sensitivity of grass carp (Ctenopharyngodon idella) and Big head carp (Hypophthalmichthys nobilis) exposed to cadmium Chloride. To this end, fishes were exposed different concentrations of cadmium in range of cadmium chloride (0, 0.2, 1, 2, 6, 10 and 15 ml/l). The mortality of treatments was calculated at intervals of 24, 48, 72, 96 hours. Analysis of the data showed the 96 h LC50 of cadmium chloride for grass carp was 4.164 ml/l and for Big head carp was 5.590 ml/l. The results of this study showed that Cadmium is highly toxic for freshwater species.