Abstract:
The food and feeding habits of Clarias gariepinus and Labeobarbus intermedius were studied from Ribb Reservoir, Ethiopia during the dry and wet seasons of 2021. The objective of this study was to generate baseline information about the diet composition of C. gariepinus and L. intermedius fish species in the newly built Ribb reservoir. The fishes were collected using hook lines and gillnets of stretched mesh sizes (4, 6, 8, 10, and 12cm). A total of 295 C. gariepinus and 203 L. intermedius fish samples were collected ranging from 30 to 72 cm in total length (TL) and 230 to 1897 g in total weight (TW) and 14.5 to 44 cm fork length (FL) and 56 to1063 g TW, respectively. From the total number of 295 captured C. gariepinus, 202 (68.4%) guts contained food items, while 93 (31.5%) were found to be empty. Similarly, from the total number of 203 L. intermedius, 132 (65%) guts contained food items, while 71 (35%) were found to be empty. The non-empty fish sample was analyzed by using the frequency of occurrence and volumetric analysis methods. Zooplankton (24.4%), detritus (22.8%), macrophyte (16.2%), phytoplankton (14.8%), and insects (11.8%) were the major diets of C. gariepinus volumetrically. Whereas, macrophytes (29.4%), phytoplankton (27.2%), detritus (14.8%), and insects (13.6%) were the major food items in the diets of L. intermedius volumetrically in the reservoir. During the dry season, C. gariepinus was mainly dependent on zooplankton (46.2%) and phytoplankton (31%) volumetrically. However, L. intermedius highly ingested phytoplankton (58.2%), insect (15.2%), and zooplankton (13.7%) volumetrically. On the other hand, detritus (42%) and macrophyte (29.7%) were the dominant diets of C. gariepinus during the wet season. Whereas, L. intermedius macrophyte (50.3%) and detritus (23.3%) were the dominant food items in the wet season. The frequency occurrence of both fish species’ diets varied significantly (χ2 test, P < 0.05) between dry and wet seasons. Similarly, the volumetric contribution of both fish species’ diets also varied significantly (independent t-test, P < 0.05) during dry and wet seasons. Schoener’s Diet Overlap Index revealed a slight ontogenetic dietary shift in the diets of both C. gariepinus and L. intermedius. Insects and nematodes were the main diets of smaller C. gariepinus, while zooplankton, detritus, macrophyte, and phytoplankton were ingested by larger C. gariepinus. The smaller L. intermedius also mainly fed on insects, nematodes, and zooplankton whereas, the larger L. intermedius shifted to macrophyte and detritus. Generally, C. gariepinus and L. intermedius fed both plant and animal origin food items and were considered as omnivorous feeders in Ribb Reservoir and recommended as C. gariepinus for aquaculture development.