Seasonal Feeding Activity and Ontogenetic Dietary Shifts of the Common Carp (Cyprinus carpio) in Lake Arekit, a Small, Eutrophic Lake in Ethiopia

Seasonal feeding activity and ontogenetic dietary shifts of Cyprinus carpio (Linnaeus, 1758) were examined using 209 fish samples from Lake Arekit, Ethiopia. Among the 209 specimens, 174 (83.3%) displayed a range of dietary items in their stomachs. The species’ feeding patterns were determined through numerical indexes (frequency of occurrence and volumetric contribution) and composite indexes (index of preponderance [IOP] and Geometric Index of Importance [GIIi]). Detritus emerged as the primary food source for C. carpio, followed by macrophytes, insects and zooplankton. A lesser amount of phytoplankton, nematodes and ostracods were also consumed. On the basis of the findings, C. carpio can be classified as a detri-omnivore, as it consumes benthic species like nematodes, ostracods and insect larvae. Seasonal fluctuations in food item consumption were noted (p < 0.05), with higher intake during the rainy season and reduced consumption in the dry season. There was a distinct ontogenetic shift in the relative importance of food items and showed significant variations in food preferences among size groups (p < 0.05). The contributions of animal-origin food categories (ostracods, zooplankton and insects) were important in the diet of the smaller size class, whereas food of plant origin (macrophytes) and detritus were more important in the diet of adults. Understanding the seasonal feeding patterns and ontogenetic dietary shifts of C. carpio in Lake Arekit provides crucial insights into their ecological role within the lake's ecosystem and highlights their adaptability to eutrophic conditions.