The application of various pollutants such as pesticides, heavy metals etc. in the aquatic environment and their deposition in the biotic system is known to cause several structural and functional changes in the biota. On the other hand, role of pesticides in promoting our health and economy are closely related. Pesticides have brought tremendous benefits to mankind by increasing food production and controlling the vectors of man and animal diseases.
At the same use of these pollutants has posed potential health hazards to the life of fishes. Blood is highly susceptible to internal and external environment fluctuations because it is the vehicle for the transport of such pollutants.
The toxic effect of pesticides to the blood of fishes has been studied by many workers. In the present investigation, the toxicity of chlorpyrifos has been observed on Erythrocyte sedimentation rate (ESR) (mm/hr) in fish, Channa punctatus (Bloch).