Risk factors associated with parasites of farmed fish in Kiambu County, Kenya

Abstract

A cross sectional study was undertaken between October 2016 and March 2017 to determine the risk factors associated with parasitism of farmed tilapia (Oreochromis niloticus) in Kiambu County, Kenya. Semi-structured questionnaires supplemented with direct observations were administered to 148 fish farmers and 260 tilapia examined for ecto- and endo-parasites. Tilapia was the main species (66.5%) farmed under semi intensive system in earthen ponds. Most (53.5%) ponds were silted, with overgrown vegetation in and around them. Many farmers (46.4%) left fish to continue inbreeding in the ponds without restocking. Most farmers (33.1%) sourced water from rivers but majority (55.7%) did not change or refill the water within a production cycle. Only few farmers drained (30.3%) and limed (32%) ponds after fish harvesting. Majority (74.6%) shared a fishing net and only a few (4.1%) of them cleaned and disinfected it after use. Piscivorous birds (58.8%) and otters (22.6%) were the main predators reported. Fish parasites recovered were the helminth, Acanthocephalus spp. (10.4%) in the intestines, Diplostomum spp. (8.5%) in the eyes and Clinostomum spp. (3.5%) in the muscles. Others were the monogeneans Dactylogyrus spp. (3.5%) and Gyrodactylus spp. (0.4%) on the gills and skin, respectively. Infestation of fish from earthen ponds (31%) was significantly higher (p< 0.05) compared to liner ponds (3.3%). Various management practices were identified as risk factors for parasitism. There is therefore need to build capacity on proper fish farm management and increase health experts in Kenyan aquaculture.