Toxicity and effects of diazinon on behaviour and some haematological parameters of African catfishClarias gariepinus

Abstract

Diazinon [O, O-diethyl-O-(2-isopropyl-6-methylpyrimidin-4-yl) phosphorothiate] is one of the most widely used pesticides in agriculture for pest control in crops and animals. The present study was conducted to determine toxicity and effects of diazinon on the behaviour and some haematological parameters of juvenile African catfish Clarias gariepinus. The lethal concentration of diazinon (96 h LC50) was 11.80 mgl−1 for test fish under a semi-static system. Fish exposed to diazinon showed behavioural abnormalities such as hyperactivity, erratic swimming, convulsion, loss of balance, depigmentation and surfacing to gulp air. Fish were exposed to two sublethal concentrations of the pesticide (1/5th LC50 = ∼2.36 mgl−1 and 1/10th LC50 = ∼1.18 mgl−1), which were selected on the basis of LC50. To estimate haematological parameters, blood was sampled on 5, 10 and 15th day. The fish exposed to sublethal concentrations of the pesticide exhibited alterations in various blood parameters. A significant dose and time de...