Background. African longfin tetra, Brycinus longipinnis Gżnther, 1864, an ornamental fish, commonly occurs in a number of African rivers. The aim of the present paper was to describe elements of ecology of this fish, not hitherto studied in the Niger River delta. Materials and methods. The fish were sampled monthly in the Jamieson River (tributary of the Benin River, the Niger delta) during dry and wet season at four stations (1994-1995). Length, weight, sex, fecundity, and food records were collected. Methods (parameters and coefficients) used (calculated) in data processing include: Kolmogorov-Smirnov test, Fulton condition factor, gonadosomatic index. Results. B. longipinnis was a dominant characid (49.0%) in the Jamieson River. It occurred in all stretches of the river throughout the year with peak abundance during the rainy season. The length frequency distribution pattern was leptokurtotic and the growth pattern was allometric for the males and isometric for the females and immature specimens. Condition factor fluctuated with season and increased with individual length of fish irrespective of sex. K-values were significantly higher in males. B. longipinnis was a mesopredator and fed mainly on insects. Fecundity estimates ranged between 160 and 1130 and about 2.26% of its body weight was utilized in egg production. Breeding activities occurred throughout the year. Conclusion. The present study contributes important data on ecology of Brycinus longipinnis living in the particular habitat of the Jamieson River, Nigeria.