Impact of pesticides is common pollutants of freshwater ecosystems where they induce adverse effects on the aquatic biota. Freshwater fish, Cirrhinus mrigala is an important carp species in Tamil Nadu region having good nutritional values. Fishes living in close association with may accumulate pesticides. In the present investigation, the toxic effects of the chlorpyrifos LC50 0.22 ppm on some enzymes (Alkaline phosphatase and acid phosphatase) of the freshwater carp fish, Cirrhinus mrigala were estimated. Increase in the gill alkaline phosphatase (ALP) level as observed in different sublethal concentrations when compared to control. The maximum increase in the gill alkaline phosphatase (ALP) was observed in the gill tissue of fish Cirrhinus mrigala exposed to 30% sublethal concentration of chlorpyrifes reared for 21 days. The results indicated the toxic nature of the pesticide chlorpyrifos. The maximum decrease in the kidney tissue acid phosphatase (ACP) was observed in the tissue of Cirrhinus mrigala exposed to 30% sublethal concentration of chlorpyrifes reared for 21 days.
