Caracterização, hábitos alimentares e reprodutivos de quatro espécies de "aracus" e considerações ecológicas sobre o grupo no lago Janauacá-AM. (Osteichthyes, Characoidei, Anostomidae)

Abstract

Giving continuity to the study of Amazon anostomids, informations concerning to the caracterization, feeding habits and reproduction of four species (Laemolyta varia, Leporinus friderici, Leporinus fasciatus and Leporinus trifasciatus) from Janauacá lake are presented. Specimens of various sizes, colected every 15 days during one and half year were analized. Whereas the species are morphologically distinct and easily identified, when growing they suffer profound modifications in their coloration pattern to the point that the young specimens are very different from the adults. All four species are omnivorous, feeding principally on aquatic insects nymphs and seeds. The species reproduce at the mouth and at the edge of the lake during the flood season (January to april) when the water from the Rio Solimões invades the varzea lakes. At this time occurs a great proliferation of the aquatic grasses, under which generally the fry lives. Further considerations are given to the morphology of the digestive tract in relation to the feeding habits and some correlations between these species and others previously studied are also presented.