Heavy metal contamination of aquatic ecosystems has been long recognized as a serious pollution problem. When fish are exposed to elevated levels of heavy metals in a polluted aquatic ecosystem, they tend to take these metals up from their direct environment. Heavy metal contamination may have devastating effects on the ecological balance of the recipient environment and a diversity of aquatic organism. In the present investigation Copper, lead, cadmium, zinc and Nickel concentrations were recorded in tissues of Oreochromis niloticus from selected study areas in 2014- 2015. Histopathological alterations in fish tissues were also studied. Gill shows highest level of metals succeeded by muscle. The distribution of heavy metal in the fish organs analyzed were in the order of Zn > Cu > Pb > Ni and Cd. Heavy metal concentration was high in koolipalayam and orathupalayam lake. Several histopathological changes were noted in muscles and gills tissue attributable to heavy metals exposure.
