Acute toxicity of heavy metal, nickel and chromium on fresh water edible fishes

Abstract

Industrial effluent are the major sources of heavy metal pollution and it is released into fresh waterbodies. Catla catla and Clarias batrachus were exposed to Nickel and Chromium for 24, 48, 72 and 96 hrs. The median lethal concentration (LC50) of nickel to Catla catla and Clarias batrachus for 96 h of exposure were 5.77 mg/l and 7.595mg/l, respectively. The median lethal concentration (LC50) of chromium to Catla catla and Clarias batrachus for 96 h of exposure were 16.468 mg/l and 34.476 mg/l, respectively. The result also revealed that mortality rate depends upon concentrations of heavy metals and duration of exposure. The acute toxicity levels were derived from LC50 concentrations of the heavy metals. Both the heavy metals produced lethality at smaller doses. Physiological responses like rapid opercular movement and frequent gulping of air was observed during the initial stages of exposure after which it became occasional. All these observations can be considered to monitor the quality of aquatic eco system and severity of pollution.