#testis.

Pyrethroid pesticides are very commonly used for pest control in agriculture fields and may reach the aquatic system through irrigation and rain. As a result many non-target organisms including fishes of the freshwater ecosystems are adversely affected. Pyrethroid insecticide cypermethrin was used for this investigation to study the histopathological alterations in testes & ovary of a fresh water fish Anabas testudineus. The acute toxicity of cypermethrin to the test fish was determined for 24, 48, 72 and 96 hours. The LC50 values by regression equation determined were 0.15 ppm, 0.20 ppm, 0.25 ppm and 0.30 ppm respectively. The sublethal concentration determined was 0.106 ppm. The fishes to this exposure period reflects significant changes in their gonads in comparison to the control fish. In the testes, Intra-lobular edema, breakage of germinal epithelium and extensive vacuolization were reported while in the ovary large intra follicular spaces and rupture of nuclear membrane in stage II oocytes were observed. In the present study, it was concluded that cypermethrin badly affect the reproductive process in the fish.