Document Type : Primary Research paper
The study was carried out to determine the prevalence, intensity and pathological effects of parasites in Chrysichthys nigrodigitatus, Chrysichthys auratus and Synodontis clarias, from Asejire Dam, a man-made lake in south-west Nigeria. A total of 250 randomly selected fish specimens consisting of 63 C. nigrodigitatus, 99 C. auratus and 88 S. clarias were sampled from January to June 2011. Fish body length, weight and sex were determined. Dissection to extract helminth parasites and histopathological examination of tissues of the intestines and stomachs were carried out. A total of 1775 parasites were recovered from S. clarias and C. nigrodigitatus. Parasite prevalence was higher in S. clarias (86.36%) than in C. nigrodigitatus (7.94%) while C. auratus were not infected. Helminths recovered included five cestodes: Paraglaridacris limnodrili, Wenyonia longicauda, Wenyonia youdeoweii, Wenyonia virilis and Caryophy-llaeus spp., and two nematodes: Procamallanus spp. and Cosmoxynema vianai. Infection in males and females was not statistically different (P>0.05). No significant difference was found in the prevalence of helminths in relation to size, however bigger sizes of S. clarias and C. nigrodigitatus were more parasitized. Pathological conditions such as lymphocytic infiltration, moderate disruption of muscular mucosa and intestinal villi, edema were found in infected fishes.