Histopathological changes in the gills of Channa punctatus (Bloch) exposed to certain organophosphate pesticide

Toxic response evaluation of a common freshwater fish Channa punctatus (Bloch) against a widely used organophosphate insecticide Malathion was assessed and evaluated at histopathological levels, taking gill as an organ for evaluation. Fishes were treated with two sublethal concentrations (10 μl/l & 12 μl/l, LC₅₀- 16 μl/l) separately. Evaluation was done after 24h, 48h, 72h & 96 h exposure. The study revealed that gills were highly sensitive to malathion toxicity and became affected within 24h of treatment. The intensity was dose-dependent. The histopathological alterations reached to its peak severity by 72h of exposure. Significantly lamellar distortion & fusion together with epithelial desquamation & necrosis were discernible changes that finally led to congestion & hemorrhage.