Abstract:
The fisheries and aquaculture sectors play important roles in food and nutrition, besides providing economic security to many people worldwide. However, parasitic infections of fish populations pose threats to these sectors. The North African catfish Clarias gariepinus (Burchell, 1822) is among the commercially important species in the fisheries production system in Kenya, but its parasite fauna is inadequately known. Therefore, this study investigated the occurrence of endo-helminths in C. gariepinus populations from Lakes Naivasha and Ol’Bolossat. Specifically, this study aimed to identify the endo-helminths infecting the catfish using morphological and molecular techniques; determine the prevalence, mean intensity, and mean abundance, and diversity indices of the fish parasites in Lakes Naivasha and Ol’Bolossat. A total of 101 specimens of C. gariepinus were collected (66 from L. Naivasha and 35 from L. Ol’Bolossat) using gill nets. Fish samples were examined for the presence of endo-helminths in various organs using a stereo microscope. The parasites recovered were washed in normal saline solution (0.85%) before being fixed in 70% ethanol (for SEM) and 96% ethanol for DNA analyses at the University of Limpopo in South Africa. Results showed seven species of endo-helminths recorded: Glossidium pedatum; Tetracampos ciliotheca; Plagiorchioidea sp.; Diplostomum sp.; Tylodelphys mashonensis; Paracamallanus cyathopharynx; and Contracaecum sp. Details of their morphological descriptions and DNA sequences are presented. Tetracampos ciliotheca, Diplostomum sp., P. cyathopharynx, and Contracaecum sp. recorded high prevalence (57-100%). Diplostomum sp., T. mashonensis (L. Naivasha), and Contracaecum sp. recorded high mean intensities (>9.75). Diplostomum sp. and Contracaecum sp. recorded the highest mean abundance (>5.57). Diversity indices in the two lakes were similar in pattern. The records of G. pedatum, T. mashonensis, T. ciliotheca, and Plagiorchioidea sp. under this study form the first biogeographical records in Kenya. The influence of water quality and seasonality on the infection indices are recommended for investigation.
