The diet of Brycinus nurse (Pisces: Characidae) from Asa reservoir, Ilorin, Nigeria

RESUMO

From November 1991 to October 1993, 980 specimens of the characid Brycinus nurse were collected from Asa reservoir to examine its diet. The diet was analyzed using the frequency of occurrence, numerical and gravimetric methods. Two hundred and sixty nine (27.45) of the stomachs examined were empty. The fish was an omnivore feeding extensively on a wide array of plant and animal food items. These consisted of 9 families, 10 genera and 10 species. The most extensively consumed plant food item was aquatic plant parts which occurred in 63.88 of the stomachs, and accounted for 6.06 by number and 12.10 by weight while the ephemeropteran, Povilla adusta was the most dominant animal food item, occurring in 50.92 of the stomachs, and accounting for 11.98 by number and 11.86 by weight. Conversely, the least consumed plant food item was Volvox occurring in 4.49 of the stomachs and accounting for 0.18 by number and 0.35 by weight, while the fish Barbus sp. was the least consumed animal food item occurring in 0.51 of the stomachs, accounting for 0.03 by number and 1.62 by weight. New food items not previously recorded such as a watermite. Aspatharia sinuata and Barbus callipterus were found in the stomach contents. The nonspecific feeding regime of the fish and its ability to utilize different food items effectively was what accounted for the prominence and wide distribution of the fish in the lake.