Parasite fauna of farmed Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) in Zombo district

Abstract

Aquaculture is an important food contributor to the global and local economy. Diseases and parasite infections have been recognized as one of the detrimental and limiting factors in the development of aquaculture. Besides, fish diseases associated with parasites constrain fish production and lower fish quality leading to low economic returns in addition to public health concerns. The occurrence of parasites for O.niloticus tilapia cultured in Zombo district is un known yet there is a growing interest in fish farming. This study was therefore conducted with the aim of investigating fish parasite species diversity with their infestation levels and examining the influence of fish size on infestation levels for tilapia. Using routine necropsy and parasitological examination procedures, a total of 40 O. niloticus fish were examined for presence of parasites. Results revealed that 55% (22/40) were infected by at least one parasite. Four parasite species: Protozoan (Trichodina spp), Monogeneans (Cichlidogyrus spp), Nematode (Contracaecum spp), and Digenean (Clinostomum spp) were recorded during the study. Clinostomum spp dominated the parasite community with a prevalence of 22.5 and mean intensity of 4, followed by Trichodina with a prevalence of 20 and mean intensity of 3, Cichlidogyrus with a prevalence of 17.5 and mean intensity of 1 and Contracaecum being the least with prevalence of 7.5 and mean intensity of 1.The low infestation levels could be attributed to the extensive fish farming system practiced by farmers which is characterized by low stocking densities of 2 fish/ meter squared. With regard to the influence of fish size on infestation levels, the study revealed that fish of smaller size (probably young fish) had fewer or no parasite infestation compared to the larger and mature fish. This could also be attributed to the long exposure time spent in culture environment by large fish hence accumulating more parasites than smaller ones.