Aim of this research is histopathological study of different salinity effects in the gill of Barbus sharpeyi. After a week adaptation, 120 fingerling fish were divide into 4 aquariums had the following different salinities 4, 8, 10 and 12 g/l and one other was contained control fishes and exposed for 96 hours. Then samples of tissues were prepared and fixed in 10% formalin. After tissue processing, dehydration, clearing and blocking, 5µm sections were prepared and stained with haematoxylin and

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... osin and studied by light microscope. Findings showed a major change in gill structure exposed to different salinity compare with the control fish. Epithelial lifting was observed in all concentrations, but high concentrations showed more severe lesions. In these concentrations epithelial hyperplasia, increased Chloride cell and mucosal cell, epithelial lifting, mucosal cell and chloride cell hypertrophy were observed. The present results, showed that salt have toxic effects in Barbus sharpeyi and result to histopathologic lesions in gill.