Isolation and identification of fungi from African Catfish (Clarias gariepinus Burchell, 1822) skin ulcers cultured in Abia State, Nigeria

Abstract

Fifty African Catfish (Clarias gariepinus) with skin ulcers were purposively sampled from farms in five local government areas (Umuahia South, Ikwuano, Umuahia North, Osisioma and Aba North) in Abia state, Nigeria. The fungi associated with the skin ulcers were isolated and identified using macroscopic and microscopic morphologies. The frequency of isolation and prevalence of the fungal genera were calculated. The infection rate of fungi on fish samples from Umuahia South, Ikwuano, Umuahia North, Osisioma and Aba North was 100%, 80%, 60%, 100% and 100%, respectively. Five fungal genera (Aspergillus, Saprolegnia, Penicillium, Aphanomyces and Fusarium) were isolated from the samples. A total of 98 fungal isolates were identified with Aspergillus spps being the highest (55), while Fusarium spps (2) and Aphanomyces spps (1) were least. The prevalence of the fungal genera isolated was Aspergillus: 70%, 60%, 40%, 30% and 40%; Saprolegnia: 50%, 60%, 60%, 50% and 50%; Penicillium: 40%, 20%, 20%, 10% and 20% in Umuahia South, Ikwuano, Umuahia North, Osisioma and Aba North, respectively, while Aphanomyces and Fusarium showed 10% and 20% prevalence, only in Umuahia South. The frequency of isolation of Aspergillus (41.7%, 75%, 40%, 52.2% and 60%), Saprolegnia (25%, 14.3%, 50%, 52.2% and 26.7%), and Penicillium (8.3%, 10.7%, 20%, 17.4% and 13.3%) varied in Umuahia South, Ikwuano, Umuahia North, Osisioma and Aba north, respectively; whereas Fusarium (16.7%) and Aphanomyces (8.3%) were found only in Umuahia South. The fungal organisms have the potential to be pathogenic. Hence, there is need for screening of African Catfish with skin ulcers, to ascertain the presence of disease-causing organisms and possibly avoid human consumption.