Aspectos de sistemática e morfologia de Schizodon fasciatus Agassiz, 1829, Rhytiodus microlepis Kner, 1859 e Rhytiodus argenteofuscus Kner, 1829 (Osteichthyes, Characoidei, Anostomidae) do lago Janauacá - Amazonas ^(*)

Variations in the colour patterns at different stages of development of Schizodon fasciatus, Rhytiodus microlepis and R. argenteofuscus are detailed. Various meristic and morphological characters, are analysed to give a more complete characterization of these species. The identification of the strange post-larval juvenile of R. microlepis once considered to be a separate genera within the Anostomidae, is discussed.