Reproductive biology and feeding habits of the catfish Clarias gariepinus (Burchell) (Pisces: Clariidae) in lake Awassa, Ethiopia

Abstract

Breeding and feeding habits of the catfish Clarias gariepinus, in Lake Awassa Ethiopia, were studied from samples collected between February 1987 and March 1988. Breeding started at the beginning of the early rains in February and continued until June, after which the proportion of breeding females declined gradually while the proportion of breeding males declined sharply. The sex ratio was not significantly different from unity, because 50.4% females and 49.6% males were caught during the investigation. The smallest ripe female in the catch was 34.0 cm total length (TL) and the smallest ripe male caught was 33.0 cm TL. The weight of ripe ovaries ranged from 11.2 to 962.0 g and the number of eggs ranged from 8,800 to 650,000 eggs. The number of wet weight of preserved eggs per gram ranged from 435 to 1176 with a mean of 669. C. gariepinus was found to be carnivorous in its feeding habit and fish was the most important food item. It contributed 81.7% of the food items of the juveniles and 86.8% of the food of the adults by volume. A cichlid fish (Oreochromis niloticus) was the most utilized prey of C. gariepinus. O. niloticus accounted for 71.0% of the food eaten by juvenile fish (16.3B35.0 cm TL) and 77.5% of the food of adults by volume. Other food items found in the stomachs of C. gariepinus include insects, fish eggs, gastropods, pieces of macrophytes, detritus and zooplankton.

SINET: Ethiopian Journal of Science Vol. 23, No. 2 (December 2000), pp. 231-246




Key words/phrases: Clarias gariepinus, food, Lake Awassa, piscivory, reproduction