We present information on the diversity of fishes in Caño La Guardia, a tributary of the Capanaparo River (Orinoco basin), a river of moderately black waters located in southeastern Apure state, Venezuela. We found 174 species pertaining to 39 families and ten orders. The orders of most importance were Characiformes (94 species), Siluriformes (34 species), Perciformes (24 species) and Gymnotiformes (12 species). Samples were collected from three types of habitat: sandy beaches, main river

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... l and sites associated with the morichito palm tree (Mauritiella aculeata). Our results showed significant differences of species composition among the habitats evaluated. Some 41 species were found only at sites associated with morichito palms, and all of those are of high value in the ornamental fish trade. This study increased the number of fishes for the Capanaparo River sub-drainage by forty species.