Histopathological study of Channa gachua exposed to sublethal concentration of malathion

This is well established fact that the exposure of pesticide leads to the significant physiological and histological changes in aquatic fauna. Therefore, ecotoxicology and histopathology have become the important areas of research for scientists, now a days. In order to investigate histopathological effects of synthetic pyrethroids, Skin, Liver, kidney, gills, and spleen of Channa gachua were examined after exposure to sublethal and acute concentration of melathion (0.8 and 1.6 mg/L) for 20 days. Fishes showed degenerative, necrotic changes and congestion of blood vessels in gill filament. Severe degeneration in secondary gill lamellae, separation of gill filament from basement membrane, proliferation of mucus cells and atrophy of gill filament were seen. Hyperplasia was found as an increased number of epithelial cells at the distal or basal portions of kidney. Few nephrons had obstructed glomerular capillary and detachment of the tubular epithelium with the surrounding tissue. Necrosis was present in hematopoietic tissue, glomerular cells, and tubular cells. Melanomacrophage centers (MMC) were scattered throughout liver and spleen. Exudates and necrosis in the splenic white pulp were observed. The liver had a low number of necrotic hepatocytes and enlarged hepatic perisinusoidal areas containing eosinophilic material. Vacuolar dystrophy of hepatocytes and hypertrophy of hepatocytes were also observed. Fish showed serious skin lesions but did not show any behavioural abnormality as compared to controlled group. Their histological recovery was also examined for next 30 days. These changes which observed during exposure were reversed after 30 days of recovery period.