Effect of Dietary Selenium Supplementation on Cirrhinus mrigala (Hamilton, 1822) Reared in Copper and/or Cadmium Contaminated Water

Abstract

The effect of selenium supplementation at 0, 75, 150, 225, and 300 mg/kg diet on reduction of copper and/or cadmium toxicity was studied in a freshwater cultivated carp, Cirrhinus mrigala. Food utilization, selected hematological parameters, oxygen consumption, and metal concentrations in the fish body and fecal matter were analyzed. The 96-h LC50 values for C. mrigala were 0.126 ppm for copper exposure, 0.563 ppm for cadmium, and 0.123 ppm for exposure to both metals simultaneously. Sublethal exposures to the metals significantly reduced consumption and growth rates, hematological parameters, and oxygen consumption in fish fed the unsupplemented diet. Equitoxic exposure of copper and cadmium together drastically reduced the physiological parameters as compared to individual exposure to either one of the metals. However, dietary selenium supplementation significantly improved the tested physiological parameters and reduced the metal burden in the fish body. Metal elimination from the body took place through the feces. Supplementation of 75 and 225 mg selenium per kg diet was required to reduce copper and cadmium toxicity when the metals existed individually in the environment. However, 300 mg selenium per kg diet was required to reduce toxicity when both metals were present together in the environment.