In the present study the toxicity of tannery effluent on economically important fish, Catla catla. Bioassays were carried out. Changes were observed after 30days of exposure, (sublethal concentration). Red blood cells, (RBC) count and Hb content decreased when compared to the control. The number of white blood cells (WBC) increased in textile effluent treated fishes. The discharge of tannery effluent with present condition into water bodies will definitely affect the fish population.
