Food and feeding habits of the Nile tilapia Oreochromis niloticus (Linnaeus, 1758) from Ribb reservoir, Lake Tana sub-basin, Ethiopia

Abstract

This study aimed to examine the food and feeding habits of Oreochromis niloticus at the Ribb reservoir for sustainable management. A total of 512 specimens were collected using gillnets of different mesh sizes. Of these, 348 (67.9 %) fish had different foods, while 164 (32.1%) fish had empty stomachs. Mud was the main food item that accounted for 89.1% of estimated stomachs and 55.1% of the total volume in the diet. Detritus and phytoplankton were the second most important food items contributing 25.1% and 14.1% of the total volume respectively. Prey items differed depending on the fish size (ANOVA, p < 0.05). The smallest-sized fish preferred detritus, zooplankton, and mud while the food items such as mud and phytoplankton were preferred by the larger-sized fish species from the Ribb Reservoir. The seasonal variations in food composition were observed (ANOVA, p < 0.05). The volumetric contribution of foods such as mud and detritus were higher in the dry season and contributed in 61.2% and 19.2% respectively. During the wet season, phytoplankton and detritus were the most important food items and their corresponding volumetric contributions were 52.3% and 42.1% of the total volume in the stomach O.niloticus Generally, O.niloticus exhibited omnivorous feeding habits in their diet from the newly established Ribb Reservoir. It is possible to conclude that food and feeding habits of O.niloticus influenced by seasons, and fish sizes from Ribb Reservoir. Therefore, water buffer zone management is needed to improve the food and feeding habits of this fish for the better sustainable utilization.