Oxyropsis is a genus of small suckermouth armored catfish in family Loricariidae, subfamily Hypoptopomatinae - the same broad group that includes the familiar Otocinclus. The three atlas species, including the flathead oto (O. acutirostris) alongside O. carinata and O. wrightiana, are recorded from Brazil, Colombia, Peru, and Venezuela, within the wider Amazon and Orinoco basin drainages. They are diminutive fish, 1.5–3 in as adults, with the flattened head, ventral sucker-mouth, and bony armor plating typical of hypoptopomatine catfish, adapted to grip rocks and wood in flowing water while grazing algae and biofilm from the surface.
Oxyropsis is far less familiar to hobbyists than its Otocinclus relatives and rarely appears in the trade under its own name; fish of this general body plan and size are prized in planted and nano aquariums as peaceful, algae-grazing cleanup crew, and the flathead oto's common name suggests occasional crossover into that trade, but consistent, correctly identified availability is not something the atlas can confirm. All three species carry a Least Concern IUCN assessment, consistent with a widespread, common component of Amazonian stream fish communities rather than a genus under particular pressure.