Parasitic infections of the gills of wild African sharptooth catfish (Clarias gariepinus).

A one-year study (January to December 2015) was conducted to identify the various parasites that infect the gills of African sharptooth catfish, Clarias gariepinus. Two hundred and forty fish (20 fish/ month) of different sexes and sizes were collected from the River Nile and its tributaries at Assiut Province, Egypt. Fish were subject to clinical and parasitological examinations. The protozoan and metazoan parasites found included Trichodina sp ., Henneguya sp ., Myxobolus sp ., monogenean trematodes and encysted metacercariae (E.M.C) of digenean trematodes.The infection rates for these parasites were 14.1%, 32.0%, 5.8%, 22.0% and 4.2%, respectively. Mixed infections with more than one type of parasite was observed in 17.1%, while single infection was seen in 43.8 % of the fish examined. The highest rate of infection was observed during the winter and spring seasons (68.3% and 60.0% respectively), while in the summer and autumn seasons the rates were 58.3% and 55.0% respectively. The total infection rates in females were insignificantly higher than in males. The infection rates were lower in larger fish. The histopathological alterations induced by the parasites, herein, represented mainly in hyperplasia of gill filaments, partial or complete sloughing of the lining epithelium, focal chondritis and submucosal vasculitis with mononuclear cell infiltration.