Food and feeding habits of the African catfish Clarias gariepinus (Burchell, 1822) (Pisces: Clariidae) in the newly built Ribb Reservoir, north-west Ethiopia

The feeding habits of the African catfish Clarias gariepinus (Burchell, 1822) were studied in the newly constructed Ribb Reservoir in Ethiopia during the dry season (January-March) and wet season (June-August) of 2021. Out of 295 fish samples collected, 202 (68.4%) contained food in the gut. Zooplankton (24.4%), detritus (22.8%), macrophytes (16.2%), phytoplankton (14.8%) and insects (11.8%) were the main diets of C. gariepinus. Zooplankton (46.2%) and phytoplankton (31.1%) were predominant in the diet during the dry season, but during the wet season, detritus (42%), macrophytes (29.7%) and insects (29.5%) were the predominant food items. The frequency of occurrence and the volumetric contribution of diet items varied significantly (p<0.05) between seasons. Schoener’s Diet Overlap Index showed a slight ontogenetic shift in the diet of C. gariepinus between different size classes. Insects and nematodes were the main diets of smaller-size classes, while plankton, detritus and macrophytes were dominant in the higher-size classes. In general, C. gariepinus feeds on both plant and animal food and is considered omnivorous in the reservoir. Keywords: Diet composition, Dietary shift, Ribb Reservoir, Volumetric contribution