The Impact of Dichlorvos -Pesticide on African Catfish Clarias Gariepinus

The toxicity of dichlorvos (18 -20 mg/L) on Clarias gariepinus juveniles (mean weight 41.6±1.2(g) and mean length 18.5±2.5 (cm) was investigated in the present study using static bioassays over a period of 96 hours. The determined 96 hours LC 50 of the exposed fishes was 17.21mg/L with lower and upper confidence limits of 15.78–18.19mg/L respectively. When the fishes were exposed there was strong evidence of stress responses characterised by hyperactive swimming with subsequent erratic with jerky movements before death which increases with time and concentration of exposure. The quality of water investigated in this study showed no change in dissolved oxygen, pH and temperature. The hepatosomatic indices (HSI) and condition factors (K) which are stress indices due to environmental pollutants decreased within 15 days of exposure and increase in concentration of dichlorvos indicating that it has detrimental effect on the liver of exposed fish with time.