Parasite dynamics in Clarias gariepinus (Burchell, 1822) in semi-arid zone of Nigeria: a two-year survey

Abstract

Parasitic infections in freshwater fish, such as Clarias gariepinus, are influenced by various environmental and host-related factors, impacting aquaculture productivity and biodiversity. A parasitological survey of 120 Clarias gariepinus specimens from Kalgwai, Dingare, and Marke were randomly collected between January 2022 and December 2023 to assess parasitic prevalence and distribution. Fish were captured using various nets and transported either fresh on ice or alive to the Biology Laboratory of Binyaminu Usman Polytechnic, Hadejia. Identification was based on morphological characteristics, while sexing was determined through physical examination of the urogenital papilla. Morphometric parameters, including weight and length, were recorded. Ectoparasites were examined using hand lens and gill dissections, while endoparasites were identified through dissection of the gastrointestinal tract. Results revealed a moderate parasitic prevalence, with females exhibiting a higher infection rate (50%) than males. Among parasites identified, Trichodina spp. showed the highest prevalence on skin and gills, while Rhabdochona spp. and Monobothrium spp.
dominated intestinal and stomach infections, respectively. Notably, haemoparasitic infection by Trypanosoma spp. was recorded only in females. Parasite prevalence was significantly higher in smaller-sized and lighter-weight fish, indicating size-related susceptibility. Seasonal variation showed greater parasitic infections during the rainy season (51.66%) compared to the dry season (31.66%).
The findings suggest that host sex, size, and seasonal factors influence parasite distribution in Clarias gariepinus from the Kalgwai reservoir, with observed parasite diversity lower compared to other studies. This study provides important baseline data for managing fish health and sustaining aquaculture practices in the region.