Anthropogenic activities has increased the discharge of various concentrations of both essential and nonessential metals into aquatic ecosystems. The present study has been conducted to determine the median lethal concentration of chromium to the freshwater fish Clarias batrachus following standard procedures and was found that 40.56ppm, 38.15ppm, 36.65 ppm and 35.50ppm for 24h, 48h, 72h and 96hours LC50 doses, whereas LC0 as well as LC100 doses were 31 ppm and 40ppm respectively. The behavioural changes include abnormal coughing and jerky movements, erratic swimming, hyperactivity changes in opercular movement, copious amount of mucus secretion all over the body and loss of equilibrium were observed. All these observations can be considered to monitor the quality of water contaminated with heavy metal salts.