Acute Toxicity of Chlorpyrifos (Dursban®) to <i>Clarias gariepinus</i> Juveniles

Abstract

The acute toxicity of Chlorpyrifos (DURSBANâ), an organophosphate insecticide to Clarias gariepinus juveniles was evaluated in the laboratory, using a 96-hour static-renewal toxicity test method. The 96-hour LC50 for the fish was found to be 3.16 X 10 -7 %, with 95% confidence limit of 1.26 X 10 -4 %. Symptoms of toxicosis observed include hyper-ventilation, irregular and erratic movements with jerks, burst swimming, loss of balance, air gulping, excessive mucus production, opercular haemorrhage, tonic convulsion was observed before death finally occurred. Heavy usage of agricultural insecticides produces detrimental effects on the fishery resources and aquatic environment. To minimize the problem of pollution brought by these chemicals, the use of selected low toxicity pesticides should be encouraged. Key Words: Clarias gariepinus, chlorpyrifos, Dursbanâ, acute toxicity. Trop. Vet. Vol.22: (1) 7-11 (2004)