Author: Miranda Ribeiro, 1908
Comments: Inhabits streams with rocky and sandy bottom; in shallow and deeper (up to 0.7 m) areas with water flow up to 70 cm per second.  Forages at night, although occasional diurnal activity is also recorded.  Grazes on microscopic algae, mostly diatoms and green algae growing on rugged and light-colored rocks, and submersed vegetation.  Chironomid and simuliid larvae, as well as tiny crustaceans, are recorded in its diet.  Before grazing on a patch with dense sediment, the fish makes wiggling head-down movements, which raise sediment and blown away by the water current.  When scraping algae off the substrate, the fish makes vigorous mouth movements and jerky movements, probably related to its mouth making alternate grazing and attaching to the substrate.  Density may reach about 0.1 fish per square meter both in shaded and sunned stream stretches (Ref. 26630).