Accumulation and histological transformation in the gills, liver, muscles, and skin in Oreochromis niloticus induced by mercury

Abstract

Specimens of Oreochromis niloticus (One control and 3 experimental groups) were fed diets mixed with different doses ofmercury (control group = free of mercury; group 1 = 500 mg/kg; group 2 = 750 mg/kg, and group 3 = 1000 mg/kg) for 60 days in orderto study its accumulation and histopathological alterations in the liver, gills, skeletal muscles, and skin. The results obtained revealedthat mercury accumulation was significantly (P gills > muscles > skin. The fish fed various doses of mercury also showed histologicalalterations in these organs. Epithelial lifting and epithelial hypertrophy were seen in the gills of the treated fish. Fusion of secondarylamellae was also apparent. The effects were more pronounced in fish fed high doses (1000 mg/kg). Necrosis of hepatocytes and portalveins was also observed in the livers of the treated fish. Irregular muscle bundles and irregularly bigger gaps between the musclebundles were evident in the skeletal muscles of fish fed diets with mercury, along with some structural changes in the skin of the fishfed mercury-mixed diets. The results obtained clearly indicate that mercury causes deleterious effects on the different organs of fish ateven low dose (500 mg/kg).