Effect Of Water Quality On The Parasite Assemblages Infecting Nile Tilapia In Selected Fish Farms In Nakuru County, Kenya

ABSTRACT

Aquaculture has been documented as the most developing food industry in Kenya with increased production since the Government initiated Economic Stimulus Programme (ESP) in 2009. However, the production has not been to a maximum level anticipated in the country, particularly in Nakuru County. This is due to the uncontrolled addition of inputs (Inorganic fertilizers, manure and fish feeds) that deteriorate pond water quality. Poor water quality is one of the most common challenges faced by fish farmers since it impedes fish production and increases the incidences of parasite infections in cultured fish, leading to extensive losses. Therefore, this study investigated the effect of water quality on parasite assemblages infecting Oreochromis niloticus Linnaeus 1758 in selected fish farms within Nakuru County, Kenya from November 2016 to February 2017. A semi-structured questionnaire was administered in each fish farm to gather information on the farm management strategies. Selected physico-chemical parameters namely: dissolved Oxygen, temperature, pH, conductivity and turbidity were measured in situ using appropriate meters. Water samples from each fish farm were analyzed for nutrients (ammonium, nitrite, nitrate, total nitrogen, soluble reactive phosphorus and total phosphorus) using American Public Health Association (APHA) standard methods. Fish samples were killed by decapitation and examined in the laboratory for ecto- and endoparasites using a compound microscope and the parasitological parameters (prevalence, mean intensity, mean abundance and diversity) calculated. The results indicated that the water quality parameters were significantly different for all the six fish farms (P0.05). The fish farms with poor water quality recorded many species of parasites infesting O. niloticus compared to others which recorded good water quality parameters. Therefore, regular monitoring and control of water quality in fish ponds is recommended to reduce levels of parasite infestations