Toxicological Effects of Heavy Metal Cadmium on Two Aquatic Species: Rutilus rutilus and Hypophthalmichthys molitrix

Introduction: Cadmium (Cd) is toxic to fish at low doses and never beneficial to an organism. As Caspian roach (Rutilus rutilus) and silver carp (Hypophthalmichthys molitrix) are two key fish species, the aim of this study was to gather data on different sensitivities of few inland fish to Cd to use them in the ecotoxicity experiment studies. Subject and Methods: All samples were exposed to the different doses of cadmium chloride (0, 0.2, 1, 2, 6, 10, and 15 ppm). Mortality was recorded after 24, 48, 72, and 96 h and the median lethal concentration (LC50) amount and its confidence limits (95%) were measured by Finney’s method of probit analysis. Results: Toxicity experimenting statistical endpoints indicated that lowest observed effect concentration in roach was higher than silver carp (2 and 1 ppm, respectively), which means that no observed effect concentration was also higher for roach than silver carp (6 and 2 ppm, respectively), and LC50 was also different between species (5.26 and 6.58 ppm for roach and silver carp, respectively). Conclusion: Our results showed that Cd is toxic for these fish, especially roach; therefore, we suggest using this fish species for toxicity experiment of heavy metals as a suitable indicator of toxicological studies.