Author: Miranda Ribeiro, 1908
Comments: Inhabits streams with rocky and sandy bottom, in places up to 0.8 m deep and with water flow up to 30 cm per second.  Forages both during the day and at night.  Grazes on microscopic algae, mostly diatoms and green algae growing on rocks and submersed vegetation.  Occasionally takes chironomid and simuliid larvae, as well as tiny crustaceans.  Before grazing on a patch with dense sediment, the fish makes wiggling head-down movements which raise sediment, to be blown away by the water current.  When grazing algae off the substrate makes vigorous mouth movements, and moves by jerky movements probably related to its mouth making alternate grazing and attaching to the substrate.  Leaves conspicuous grazing marks on exposed rocks.  May re-graze a given spot by moving backwards.  Density may reach about 1 fish per square meter in stream stretches shaded by the forest and 2.5 fish per square meter in sunny stretches (Ref. 26630).