Toxicity of lower than permissible levels of chromium (VI) to the freshwater teleost Nuria denricus

The impact of chromium (VI) on the freshwater teleost Nuria denricus in concentrations ranging from 0 to 100 mg litre −1 was studied by computer-aided long-term static bioassays. The metal induced marked changes in the fishes' swimming and feeding patterns. It caused erosion of fin rays, ulceration, and finally death. The median lethal dose (LD 50 ) and safe concentration (SC) values obtained from the present experiments reveal that the prevailing allowable levels of chromium in drinking water, irrigation waters and effluent discharges are too high and may lead to environmental damage.