The feeding ecology of bagrid species in River Ase, Niger Delta, southern Nigeria

Abstract

The feeding ecology of seven bagrid species was studied between March, 1982 and February, 1984. A summary of the food items and condition factors (kf) in relation to sized groups were described for all the seven species while feeding intensity are to sized groups, diel and monthly variations in feeding intensity are provided only for Chrysichthys auratus longifilis (Geoffrey St. Hilaire, 1908) and C. nigrodigitatus (Lacepede 1803) due to data. Variations in food items between dry and rainy seasons were not remarkably different. There were differences in the feeding habits of different sized groups in C. auratus longifilis while in C. nigrodigitatus, all the sized groups consumed mainly detritus. Both C. auratus longifilis and C. nigrodigitatus fed both day and night. Feeding intensity was highest in C. auratus longifilis from 2100 to 2400 (h) and from 2400 to 0300(h) for C. nigrodigitatus. Based on the food items, Bagrus bayad macropterus Pfaff, 1933 was mainly piscivorous in diet while B. domac niger Daget, 1954 fed on fish and decapod crustaceans. C. auratus, C. nigrodigitatus, C. furcatus (Gunther, 1864) and Auchenoglanis occidentalis (Cuvier and Valencienness, 1840) were omnivorous bottom feeders. Clarotes laticeps fed on fish and detritus. The feeding ecology of bagrid species has been discussed and compared with the findings of earlier studies conducted elsewhere.

Key Words: Bagridae, feeding ecology, Niger Delta, diets, seasonality

Tropical Freshwater Biology 11 (2002) 47-68