Food and Feeding Habits of the Common Carp (Cyprinus carpio L. 1758) (Pisces: Cyprinidae) in Lake Koka, Ethiopia
Keywords:
Cyprinuscarpio, Lake Koka, Seasonal and Ontogenetic Variation in Diet, EthiopiaAbstract
Feeding habits of Cyprinus carpio was studied in Lake Koka, Ethiopia, in April and May (dry months) and July and August (wet months), 2011. The objective of the study was to identify the diet composition, seasonal variation in diet and ontogenetic dietary shift. Gut contents of435 fish were analyzed using frequency of occurrence and volumetric analysis. In frequency of occurrence method the number of gut samples was expressed as a percentage of all non-empty stomachs examined while in volumetric method the volume of each food category was expressed as a percentage of the total volume of the gut contents. Detritus, insects and macrophytes were the dominant food categories occurring in 97.0%, 85.2% and 53.3% of the guts and comprising 39.8%, 36.4% and 12.4% of the total volume of food items, respectively. The remaining food categories were of low importance in the diet. The frequency of occurrence and volumetric contributions of the different food categories of C. carpio significantly varied (U-test, p<0.05) during the dry and wet seasons. During the dry season, insects and detritus were important food categories, occurring in 94.4% and 98.6 of the guts and comprising 42.3% and 36.1% of the total volume of food, respectively. During the wet season, detritus was the most important food category. It occurred in 93.9% of the guts and accounted for 48.8% of the total volume of food. Insects and macrophytes were also important during the wet season, occurring in 68.2% and 74.3% of the guts and comprising 23.6% and 22.6% of the total volume of food, respectively. The contributions of animal origin food categories were important in the diet of juveniles whereas food of plant origin were more important in the diet of adults. However, there were no significant variations in the diet of individuals in the different size classes. Based on the results, it was concluded that C. carpio was omnivorous in its feeding habits in Lake Koka with considerable seasonal variation but insignificant onto genetic change in its diet.