Pseudolithoxus is a genus of small armoured suckermouth catfish in the family Loricariidae, found in fast, rocky rapids of Amazon and Orinoco tributaries in Venezuela and Brazil. The atlas covers 7 species ranging from about 1 in up to 6 in, and the genus is built for life in strong current: an elongated, flattened body, a sucker-disc mouth for gripping rock, and bristly odontode whiskers along the cheeks and snout that are more pronounced than in many other plecos. These rheophilic catfish graze algae and biofilm from stone surfaces in highly oxygenated, fast-moving water rather than the slower backwaters many other loricariids favour.
Several species are well known in the hobby by their L-number trade codes, including L235 (Pseudolithoxus anthrax) and L244 (P. dumus), alongside the tiger pleco, P. tigris, prized by specialist pleco keepers for bold pattern and compact size. Their rapids origin means they do best with strong flow and high dissolved oxygen, conditions that are harder to replicate than a standard community setup. The IUCN picture includes species from Least Concern through Near Threatened, Data Deficient, and one Endangered, a spread consistent with a genus of narrow-range rapids specialists that can be badly affected by dam construction or altered river flow even where they are not directly targeted by trade.