Pesticides are an integral part of present day agricultural technology. They are greatly contributing towards increasing world food supply by protecting the crop yield. Due to intensive development of agriculture in recent years and rapid growth of industrialization in our country, there has been a great increase in manufacture and utilization of fertilizers, pesticides, petrochemical products, detergent and other synthetic chemicals and agricultural wastes pose a serious threat to the water ecosystem and aquatic life. Monocrotophos is one of the organophosphorous pesticide used in this study. The median lethal concentration(LC50) of MC to fish L. rohita for 96 hour was found to be 45.1 ppm.In sublethal concentration(1/10th of LC50 96 hour value, 4.51ppm) fishes were exposed for 24, 48, 72 and 96 hrs, 10 days, 20 days and 30 days.A significant decrease in erythrocyte (RBC), Haemoglobin (Hb),mean cellular volume (MCV), mean cellular haemoglobin (MCH) and packed cellular volume were observed throughout the study period when compared to their controls. In contrast, leucocyte (WBC) were increased in this study period.It is essential for assessing the ecological risk of these pesticides.
