TOXIC EFFECTS OF COPPER AND MERCURY ON FOOD-INTAKE, GROWTH AND PROXIMATE CHEMICAL-COMPOSITION IN HETEROPNEUSTES-FOSSILIS

Heteropneustes fossilis was exposed to copper (750 ppb) and mercury (6 0 ppb) individually show-ed significant decrease in food consumption a nd growth. Animals exposed to copper + mercury (56 ppb) consumed and g rew at the rate of 31.2 and 4.8 mg/g/day as against 37.8 and 11.4 mg/g /day in the control animals. The efficiency with which the food was co nverted into flesh also showed significant reduction. Exposure of anim als to the media containing both copper and mercury produced about 50 and 40% reduction in the rate and efficiency of conversion compared wi th the animals exposed to metals individually indicating a synergistic effect of copper and mercury. Similar trend was observed in the bioch emical composition also.