Prevalence and Mean Intensity of Ectoparasite Infections in Pond Reared Nile tilapia ( Oreochromis niloticus ) in Morogoro, Tanzania

A cross sectional study was carried out between September 2007 and September 2008 to investigate the prevalence and mean intensity of ectoparasite infections on the gills and skin of Nile tilapia ( Oreochromis niloticus ) in Morogoro, Tanzania. A total of 229 fish from 19 ponds were studied. Trichodina spp. and Monogeneans were the only ectoparasites observed. Overall prevalence of ectoparasites in the study area was 68% and the average mean intensity was 5.3. Trichodina spp. were more prevalent (P<0.05) than Monogeneans. Gills were more affected with parasites than the skin (P<0.05). There was no strong relationship between water quality and prevalence and mean intensity of parasites. Prevalence and mean intensity varied in different ponds due to different management practices and the knowledge of fish husbandry. Parasite infection was significantly higher in urban than in rural areas (P<0.05). There is a need for farmers to be trained on proper fish husbandry and pond management in order to reduce the risk of parasite multiplication in the ponds and hence infection rate. Keywords: Freshwater fish, Trichodina spp., Monogenean, diseases