Biochemical effects of Organophosphorus pesticide, Quinalphos on freshwater fish, Oreochromis niloticus (L.)

Quinalphos is a synthetic organophosphorus broad-spectrum insecticide, widely used to control insect pests in agriculture. In the present study, an attempt has been made to investigate the biochemical effect of quinalphos on different tissues like liver and brain of the edible freshwater fish Oreochromis niloticus (L). The O. niloticus were exposed to sublethal concentrations of quinalphos for two different periods of time (1 day and 5 days). From the result, the protein content and acetylcholinesterase enzyme in the tested tissues of O. niloticus was found to decline with increasing exposure periods of quinalphos. Activity of antioxidant enzymes glutathione S-transferase and catalase shows a significant change in their level compared to the control. The present study suggests that quinalphos in sublethal dose altered antioxidant balance of the fish which cause severe oxidative stress. Therefore, the use of quinalphos in the agriculture may be a threat to aquatic population and also other organisms including human beings via food chain.