Abstract

A total of 250 randomly selected fish specimens consisting of 72 Clarias gariepinus and 51Clarias pachynema from Ogun River around the cattle market, Isheri, Ogun State. 73 C. pachynema and 54 C. gariepinus from Asejire Dam (which has not been reported to be polluted) in south-west Nigeria were sampled for helminth infection between September 2008 and February 2009. All helminthic infections observed and recorded were restricted to the stomach, intestine and gill chamber. The helminths recovered included three cestodes,Wenyonia sp., Polyonchobothrium sp. and Pleurocercoid larva, a nematode, Procamallanussp. and one digenean, Clinostomum sp. Prevalence and mean intensity of parasitic infectionwere higher in specimens from the Ogun River than those from the Asejire Dam. Overall, parasite prevalence of 75 and 45.1% were recorded for C. gariepinus and C. pachynema from the Ogun River, respectively, while 25.9 and 31.5% were recorded for C. gariepinus and C. pachynema, respectively, for the Asejire Dam. Male C. gariepinus from the Ogun River had the highest infection rate (76.5%), while those from Asejire Dam had the lowest (21.43%). No significant difference in the prevalence of parasitic infection in relation to the host sizes (P > 0.05) was recorded; however, largest size fishes had no parasitic infection. Clinostomum sp.was found only in C. gariepinus and C. pachynema from Ogun River.

Key words: Sharptooth catfish, Clarias pachynema, helminth parasites, south-west Nigeria.