ECTOPARASITE INFESTATION OF NILE TILAPIA (OREOCHROMIS NILOTICUS) IN CAGE CULTURE AT MPAKADAM, GHANA

Abstract

The aim of the study was to identify and estimate the prevalence and intensity of the infestation of common ectoparasites on Nile tilapia (Oreochromis niloticus) from cage culture systems at Mpakadam in the Asuogyaman District of the Eastern Region of Ghana. A total of 210 individual fish samples were collected. The total length of the samples was measured and they were grouped into phases according to their sizes as Initial Phase (0.1cm - 7.0cm), Intermediate Phase (7.1cm - 12.0cm) and Final Phase (12.1cm - 18.0cm). Each sample was then examined for ectoparasites with the aid of a light microscope and hand lens. Specific parts of the fish, thus the skin, gills, fins and eyes were examined. Measurement of water quality parameters of the water in the cages were also taken bimonthly throughout the study period. The study was conducted from December, 2016 to April, 2017. Out of 210 fish samples examined, 94 samples representing 44.76 % were infested with ectoparasites. 42.30% of the 78 samples within the initial phase were infested, 43.75 % of 96 samples with the intermediate phase were also infested, while 52.80 % of 36 samples of final phase were infested. Six species of ectoparasites namely, Trichodina sp., Diplostomum sp., Argulus sp., Dactyogyrus sp., Lernaea sp. and Ichthyophthirius miltifilis were identified. Parasites were found on all examined parts of the fish with the skin being the most infested part of the host. The prevalence and the mean intensity (MI) of parasites on the host were relatively low. All physico-chemical parameters measured were within the optimum values for tilapia culture as compared to the standard requirement for tilapia culture under cage system. The level of intensity of ectoparasites observed in this study, arguably will not pose a major threat to the fish on the farm in the area. However, critical attention should be given to the farm by employing best aquaculture management practices to prevent disease outbreaks due to intensification of ectoparasites.