The feeding habit of the CyprinidaeRastrineobola argenteain its new habitat, lakes Bulera and Ruhondo, two Rwandan lakes (Eastern Africa)

Abstract

Rastrineobola argentea Pellegrin 1904, a small pelagic endemic cyprinid from lake Victoria was introduced into lake Bulera (Rwanda) in 1991 in order to develop a fishery. From there, it accidentally colonized lake Ruhondo. To study its biology in its new habitat, samples were collected in 2007 and size and the feeding habits of the fish were analyzed. R. argentea is smaller in lake Bulera (41.8 ± 6 mm) than in lake Ruhondo (mean total body length: 72.6 ± 15 mm). The mean total body length in lake Bulera is less than its size at the first maturity in lake Victoria (47 mm). Differences in size structure of fish between lakes Bulera and Ruhondo is attributed mainly to the food availability in the two lakes. In lake Bulera, the fish feeds on six food items with plant remnants dominant. In lake Ruhondo, R. argentea is a zooplanktivorous feeder like in lake Victoria. The dominant prey is a cladoceran species, Daphnia sp. which has not been observed in lake Bulera during the sampling period.