Histopathological Changes in Vital Organs of Oreochromis niloticus in Fish Farm Irrigated with Drainage Water in El Fayoum Province, Egypt

This chapter aimed to investigate the impact of heavy metals pollution in a fish farm in El Fayoum Province on some vital organs tissues (liver, gills, intestines and muscles) of Oreochromis niloticus (L.). Pollution of aquatic environment is a serious and growing problem [1], which is usually brought about by increasing domestic, agricultural, commercial and industrial activities of man. Fish samples of Oreochromis niloticus (L.) were caught during year 2006 from a fish farm in El Fayoum Province for monitoring bioaccumulation of some heavy metals (Fe, Mn, Cu, Zn, Pb and Cd) in the liver, intestine, gills and muscles of the fish and their effect on the tissue organs. The present study revealed that, the concentrations of zinc and lead were higher than the permissible level in the liver, intestine, gills and muscles of Oreochromis niloticus (L.). The concentrations of copper and cadmium were higher than the permissible level in the liver for copper and in the liver and intestine for cadmium. The liver, gills, intestine, and muscles all showed a number of histological abnormalities. Hepatocytes in the liver sections showed signs of degeneration and necrosis. Necrotic patches and expanding deterioration filled the hepatic tissue. The fish gills were examined under a microscope, which revealed edema in the primary and secondary lamellae, full fusion of the secondary lamellae, and telangiectasis (blood cell congestion in the ends of the secondary lamellae). The fish's gills also experienced considerable bleeding. The hisopathological changes in the intestine included degeneration and necrosis of epithelial cells of mucosa, aggregation of inflammatory cells in submucosa and destruction of muscularis. Skeletal muscles exhibited different stages of degeneration, atrophy, necrosis and infiltration of inflammatory cells. The heavy metals accumulated in the vital organs of Oreochromis niloticus (L.) and caused many pathological lesions. So, we recommend treatment of drainage water before its entrance into fish farms.