Infestation of ectoparasites on Nile tilapia (Oreochromis niloticus) in aquaculture production in the Ashanti region, Ghana

Abstract

A survey was carried out to investigate the prevalence and mean intensities of ectoparasites infestation on the gills and skin mucus of Nile tilapia (Oreochromis niloticus) in some selected fish farms in the Ashanti region of Ghana. Pond water quality was also determined. Oral on-farm interviews on pond management practices were carried out on the farms. The results obtained revealed three types of ectoparasites namely; Trichodina sp., monogeneans and Tetrahymena sp. of which the first two were prevalent on most farms. Tetrahymena sp. was found on one farm. The physico-chemical parameters and management practices were very similar in all farms. There were no strong relationships between ectoparasite prevalence and intensity and the physico-chemical properties and the management practices on the farms. the ectoparasites occurrences in infected farms might have been due to a chance effect. The general low prevalence and intensities of ectoparasites recorded in the infected farms is an indication that the Nile tilapia has a biotic mechanism which might have enabled it to reduce the growth rate of ectoparasite intra-population. The ectoparasites do not seem to pose a threat for the aquaculture industry in the Ashanti region as observed in this study, but measures have to be taken to secure the industry from unforeseen incidents, for instance in the introduction of non-endemic parasite species in the future.