Seasonal study of the relationship between the condition factor and the monogeneans parasite density of Heterobranchus isopterus Bleeker, 1863 and Clarias gariepinus (Burchell, 1822) fished in the Bagoué River (North-Western, Ivory Coast).

A comparative study on the relationship between condition factors and parasite density of Heterobranchus isopterus and Clarias gariepinus was conducted during the wet and dry seasons. Specimens were collected from the Bagoué River from August 2020 to July 2021. Two hundred eighty-four specimens of H. isopterus and 272 specimens of C. gariepinus were collected from all stations during both seasons. The standard length and weight of the fish were recorded and the condition factor was calculated for each individual. The gills were examined under a binocular loupe and the monogeneans were collected. Parasite counts showed that for both host species, the total number of parasites was higher in the dry season than in the wet season (p < 0.05). The correlation coefficient was determined to investigate the relationship between the condition factor and the total number of parasites. A significant positive correlation was observed between the condition factor and the number of parasites in both host species during the wet season. A negative correlation was observed in both hosts during the dry season. The information from this study could be taken into consideration in the sanitary management of the fish farming industry. The dry season could be considered as the season with favorable conditions for the development of most parasite species.