Fish, Machado River basin, Cacoal urban area, state of Rond nia, Brazil.

The Pirarara and Tamarupa rivers are two urbantributaries of the Machado River in Cacoalmunicipality, state of Rond nia (RO), Brazil.Here we report a list of species of fishes fromurban areas of Cacoal, being the firstichthyological study in this region. Field work atCacoal was carried out from November 2004 untilJuly 2005, using gill nets, casting nets, and longlines. Two hundred and twenty-two specimenswere collected, and are distributed in 48 species,14 families and 4 orders. The most representativeorder was Characiformes, with seven families and23 species, followed by Siluriformes, with threefamilies and 20 species.