Özet:

Heavy metal exposure to biota has become a severe thread to the environment, as its bioaccumulation, toxicity and persistence is happing at an alarming rate. Heavy metal presence in water bodies has been reported by various researchers. Henceforth their exposure to aquatic organisms is certain. An investigation on the possible toxicological impact of Zinc sulphate on fish Clarias batrachus is carried out in laboratory. Histology of gall bladder was used as a marker for evaluation of toxicity after sub lethal exposure. Fish were exposed to sub-lethal concentrations of 5mg/L, 10mg/L and 15mg/L for 20 days. Simultaneous control was also maintained. Principle histological alterations were deformities in the normal structures of columnar epithelial line, muscular layer, and mucosal folds. 15mg/L and 20mg/L exposure of zinc sulphate altered the sub mucosa besides leading the formation of bile crystals, an indication of water loss. The severity of histopathology was exposure dependent. Histopathological alteration in gall bladder can be regarded as sensitive biomarkers of Zinc sulphate toxicological manifestations hence can be utilized for ecotoxicological biomonitoring of aquatic bodies.

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