STUDIES ON THE HISTOPATHOLOGICAL EFFECT OF ZINC SULPHATE ON GOLD FISH CARASSIUS AURATUS

Purpose: Heavy metal in the aquatic environments has been as a potential threat to the aquatic organisms including fishes. Metals are known to inhibit the several biochemical and physiological mechanism vital for fish metabolism. In recent years metal concentrations were found to be raised in aquatic environment, due to discharge from industrial waste, agriculture and urban sewage. As a result, aquatic organisms are exposed to elevated levels of heavy metals in the coastal environment. Hence, the aim of the present study was to evaluate the effect of zinc sulphate on gold fish Carassius auratus under laboratory condition. Method: The experiment was carried out with three groups. Group I was kept as control which is free from zinc sulphate and the remaining group II and III were supplied with sub-lethal concentration of zinc sulphate 10 mg/l and 15 mg/l respectively. Fishes were exposed to these concentrations for 15 days. After the durations, the brain, liver, gills and ovary were dissected out and fixed in 10% formalin for histopathological study. Hematoxylin and Eosin were used to stain nucleus and cytoplasm of the cells. Stained slides were observed under research microscope and photographs were taken. Results: The histopathological studies have revealed that severe damage have been noticed in gills followed by liver, brain and ovary tissue, because gills come in immediate contact with environment. The destructive changes have been directly related to both concentration of doses and the period of exposure. Conclusion: The heavy metal toxicity has to be controlled or else it would affect the aquatic ecosystem and in turn other natural resources and causes toxicity to plants, animals and humans.