International Journal of Scientific & Engineering Research Volume 3, Issue 7, July-2012 1 ISSN 2229-5518 IJSER © 2012 http://www.ijser.org Diplostomum Parasites Affecting Oreochromis niloticus in Chepkoilel Fish farm and Two Dams in Eldoret-Kenya Kembenya E. Migiro, Matolla G. K, Ochieng V. Ouko and Ngaira M. Victor. Abstract- The Diplostomum parasite completes its life-cycle in fish eating birds, but spends considerable time in the eye vitreous humor of many fresh water fishes. Its infection in fish causes severe ocular pathology, and leads to increased susceptibility to predation. A study on Diplostomum parasites was conducted at Chepkoilel University with an objective of assessing its parasitic indices and effects on O. niloticus. A total of 40 fish were collected from the fish farm and 155 from the dams between November 2010 and January, 2011. Fish were weighed and length measured to ascertain their condition factor. The fish were observed for the Diplostomum parasite to ascertain parasitic indices in the different habitats. The parasite abundance was related to fish size and condition factor to determine parasite’s effect on O. niloticus. Fish were found to have a parasitic prevalence (%) of 100, 84 and 66 in Kerita dam, Kesses dam and Chepkoilel fish farm. Parasite mean intensity was 12, 9 and 14 respectively. The wellbeing of the fish was not compromised by the parasites, as was seen in the correlation between condition factor and parasite abundance. There was a Pearson correlation of P = 0.357, 0.516 and 0.565 in Kerita dam, Kesses dam and Chepkoilel fish farm respectively. The dams and the fish farm did not pose significant difference in the parasitic indices, probably due to their proximity. There was seen equal abundance in both fish sexes, implying no sex preference in infection. Keywords - Diplostomum, Oreochromis niloticus, parasite indices, Condition factor. 1 INTRODUCTION T HE metacercariae of Diplostomum spp lives in the eye vitreous humour and the lenses of many freshwater fish without undergoing encystation. Diplostomum sp. is widely distributed and one of the commonest parasites of freshwater fishes. This is to some extent due to the acceptance by the parasite of a wide range of hosts at all stages of the lifecycle and also because of extensive dissemination of parasite eggs through the migration and local movement of fish-eating birds. Its infection in fish leads to severe ocular pathology, which increases vulnerability to predation. This disease caused by the parasite, diplostomiasis, parasitic cataract or eyefluke disease is caused by invasion of the eye by larval stage of the parasite which becomes established and grow within the vitreous (Pike and Lewis, 1994). Diplostomum sp. utilizes many fishes as second intermediate host. Several fish eating birds e.g. heron (Ardea purpurea) are primary hosts of the parasite (Parpena, 1980). Their distribution is in many temperate areas of North America, Europe, Asia and Africa (George, 1987). 2 METHODS ———————————————— Kembenya E. Migiro is currently working with the Kenya Marine and Fisheries Research Institute (KEMFRI), P. O Box 3259 Kisii -0720592917. E-mail:ekembenya@yahoo..com Matolla G.K is currently working as a lecturer in Chepkoilel University College. Ochieng V. Ouko and Ngaira M. Victor are currently master students at Chepkoilel University College. P.O Box 1125-30100 Eldoret- Kenya.01123456789.