Aquatic Biodiversity Research Centre, Dept. of Advanced Zoology and Biotechnology, St.Xavierâ€™s College (Autonomous), Palayamkottai â€“ 627 002, Tamilnadu, India
The hazardous effect of heavy metals on the histopathology of selected organs of the freshwater fish common carp (Cyprinus carpio L.) was investigated. Gill, liver, kidney and flesh samples were collected after 32 days of exposure to a sublethal concentration of 5 mg/L of combined (Cd + Pb + Cr + Ni) metal solution containing 1.25 mg/L of each metal ion (1/10th of LC50 / 48h) was analyzed by using light microscopy. The main histopathological changes observed in the gill were edema and lifting of lamellar epithelia. The liver of control fish exhibited a normal structural pattern, while the fish exposed to heavy metals showed vacuolation, presence of hemosiderin and fibrosis. The findings in kidney exhibited the presence of macrophages with lipofuscin granules accumulated in the affected cells. In flesh samples lesions and granulomas were observed. The investigation of histological changes in organs of fish is an accurate way to assess the effects of xenobiotics compounds in experimental studies. This investigation presents a reliable indicator of the aquatic ecosystem contamination and the possible negative impact of the surrounding environment.