PARASITOFAUNA OF FIVE FRESHWATER FISHES IN A NIGERIAN FRESHWATER ECOSYSTEM

Sa？etak The parasitic fauna of freshwater fishes of the Warri River, Delta State, Nigeria, with reference to their prevalence, intensity and differences in metazoan parasites between fish sexes, was investigated. A total of 85fish samples comprising of 21 Tilapia zillii (Cichlidae: Perciformes), 23 Synodontisclarias (Mochokidae: Siluriformes), 23 Chrysichthys nigrodigitatus (Claroteidae: Siluriformes), 16 Hepsetus odoe (Hepsetidae: Characiformes)and 2 Clarias anguillaris (Clariidae: Siluriformes) collected from the Warri River, Delta State, Nigeria, were subjected to parasitological examination.The overall metazoan parasite prevalence was 32.9%. The metazoan parasites recovered were mainly the acanthocephalans: Neoechinorhynchusprolixum, Pomphorhynchus spp., Acanthocephalus spp. and unidentified acanthocephalan, and nematodes: Camallanus polypteri, Capillariapterophylli, C. cichlasomae, Procamallanus laeviconchus, Philometroides africanus and Railletnema synodontis. Although the acanthocephalans constituted 75.6% and nematodes 22.2% of the parasites recovered, thenematodes had the highest prevalence (23.5%) compared to the acanthocephalans (9.4%). Similarly, variable prevalences were observed for the other metazoan parasite taxa recovered, namely trematoda; Clinostomumcomplanatum (1.2%), Leech; Pisciola geometra (2.4%) and Crustaceans (1.2%). The highest parasite prevalence (39.1%) was observed in S. clarias, while the least (23.8%) was observed in T. zillii. Generally, the prevalenceof parasites was higher in female (35.7%) than in the males (31.6%), although statistically no significant difference was observed in the prevalence by sex (X2 = 0.145, P = 0.807). The relatively high overall parasite prevalence in fishes inhabiting the Warri River may be attributed to the relatively high level of pollution