Histopathological effects of cypermethrin on gill, liver and kidney of fresh water fish Clarias gariepinus (Burchell, 1822), and recovery after exposure.

Gill, liver and kidney of Clarias gariepinus were examined histologically after exposure to sublethal concentrations (10.05, 20.10 and 30.15 microg/L) of cypermethrin for 10 days. Histological recovery was also studied by maintaining the pesticide-exposed fish in a fresh water system for an additional 10 days. Epithelial hypertrophy and hyperplasia, epithelial lifting, oedema, fusion of secondary lamellae, necrosis and desquamation were histopathological changes in the gills of fish exposed to cypermethrin. Hepatic lesions in the liver tissues of fish were characterized by cloudy swelling of hepatocytes, lipoid vacuoles, pycnotic nuclei and focal necrosis. Epithelial hypertrophy, narrowing of the tubular lumen, atrophy of the glomerulus, broader Bowman's capsule, necrosis in the epithelial cells and pycnosis in the hematopoietic tissue were observed in kidney tissues of fish. These lesions grew with increasing concentration. Although some of the changes were reversible, the rest were less pronounced after a recovery period; a period of 10 days was not long enough for complete recovery.