Parasites as Bioindicator for Health Status and Environmental quality of Freshwater Fish species in Ekiti State, Nigeria

The prevalence of parasites occurring on and in the internal organs of fish species was studied. Fish species (Oreochromis niloticus, Clarias gariepinus, Tilapia zilli) were randomly obtained from fishermen landing at the jetties of Ado, Ero, Ogbese, Ikun and Egbe dams, in Ekiti state. Samples were dissected; smears for the identification of ectoparasites were taken directly from the gills, operculum and skin. The parasites were excised, identified and counted. Nematode parasite with the total sum of 164(29.6%) was the most abundant parasite occurring in all the dams. This was followed by Trichodina sp (Ciliophora) with total abundance value of 147(26.5%) in all the dams. Acanthocephalan, Gyrodactylus sp, Dactylogyrus sp, Diphyllobothrium latum and Clinostomum sp have abundance values of 26 (4.7%), 27(4.9%), 21(3.8%), 146 (26.4%) and 23(4.2%) respectively with Dactylogyrus sp (Monogenea) being least abundant, 21(3.8%), in all the dams. The overall parasitic prevalence from the different dams showed that Ado dam had the highest parasitic infection with 27.3% which suggests that Ado dam has the lowest water quality. There is need for constant surveillance in rivers and reservoirs to detect early signs of parasitic infection. Viable preventive measures against fish parasitism in Nigerian freshwater bodies are highly recommended.