Fish fauna of small streams of the Catua-Ipixuna Extractive Reserve, State of Amazonas, Brazil

This study was conducted in an Amazonas state conservation unit, the Catuá-Ipixuna Extractive Reserve (Catuá-IpixunaRESEX). The main purpose was to provide an ichthyological survey of its small streams, all them tributaries of theSolimões River. Nine small streams (up to 4 m width and 1 m depth) were sampled in September 2006. A total of 1,525specimens were captured, belonging to 78 species, 24 families and eight orders. Eight species had higher abundancesand represented altogether 61.4 % of all collected specimens (Hemigrammus belotii, Microphilypnus amazonicus,Physopyxis ananas, Apistogramma agassizii, Elachocharax pulcher, Apistogramma cf. cruzi, Gladioglanisconquistador and Copella nigrofasciata). Based on the high number of singletons and doubletons present in oursamples, as well as the estimated number of species for those streams (106 spp.), we believe that the total fish speciesrichness present in the Catuá-Ipixuna Extractive Reserve may be considerably higher than indicated by our samples.This seems especially true when considering the dimensions of the Catuá-Ipixuna RESEX and the dense hydrographicnetwork present in the area