In the present study, an attempt has been made to examine the toxic effect of cypermethrin, a synthetic pyrethroid exposed to freshwater fish Channa punctatus. The fishes were exposed to sublethal concentration of 0.08 mg/L for 15, 30 and 45 days. The gills of the fish plays vital role in respiration and are an important organ with specific functions which are highly sensitive to many factors. The chloride cells present in epithelia of gills plays main role in these functions. Transmission electron microscopic observations in experimental fishes showed accurate alterations in fish gills when compared to control. The pavement cells appeared irregular with a considerable loss of microridges which leads to irregular blood spaces and blood congestion as well as hyperplasia and lamellar fusion. Hyperplasia was often accompanied by extensive proliferation of both mucous and chloride cells. Chloride cells are enlarged and have a large apical surface and come in direct contact with the external medium.