Abstract

George Davison, Victor Sebastian and Lebechi

A study was undertaken to assess the prevalence, mean intensity, abundance and seasonality of parasites of fish in a natural, freshwater, tropical lake, southeast Nigeria. A total of 1191 fish specimen belonging to four families (Cichlidae, Bagridae, Hepsetidae and Channidae), seven genera and nine species were collected from the lake and examined for parasites. Eleven (11) species of parasites comprising metacercariae of three digenetic trematodes, one cestode, five nematodes and two acanthocephalans were isolated. Clinostomoides sp. showed the highest range of sites of infection, and the operculum carried significantly more worm burden (F = 196.843, d.f. = 5, p = 0.000) than other sites infected by this parasite. Prevalence ranged from 0.7% in Clinostomum tilapiae infection of T. zillii to 71.7% in Neochinorhynchus sp.2 infection of Hepsetidae fasciatus with an overall prevalence of 59.5%. Mean intensity ranged from 1.0 ± 0.0 in Clinostomoides sp. and Proteocephalus sp. infection of P. obscura and Anemone occidentalis, respectively, to 76.5 ± 29.7 in Neoechinorhynchus sp. 2 infection of H. fasciatus. Neoechinorhynchus sp. 2 infection also had the highest mean abundance (54.90 ± 2.74) while the lowest was recorded in the Clinostomoides sp. infection of H. fasciatus. Patterns of infection were significantly different in the prevalence and abundance of Clinostomoides sp; Camallanus sp.3 and Neoechinorhynchus sp.1 while mean intensity was comparable in all cases.