Leiarius is a genus of large long-whiskered catfish in family Pimelodidae, native to major river systems of the Amazon and Orinoco basins across Brazil, Colombia, Guyana, Peru, Venezuela, and Bolivia. The 4 species in the atlas are substantial predators, 17–31.5 in, with the smooth, scaleless, elongated body, flattened head, and long paired barbels typical of pimelodid catfish, built for hunting fish and other prey by scent and touch in murky water.
The Marbled Shovelnose Catfish (Leiarius marmoratus) is the species most familiar to aquarists, valued in large-tank and pond keeping for its bold marbled pattern and food-motivated personality, and it is also raised commercially, including as a parent in hybrid pimelodid crosses sold in the ornamental trade. The Sailfin Pim (L. pictus), Tiger Pimelodus (L. arekaima), and Longbarb Catfish (L. longibarbis) are far less commonly kept. Because adults reach nearly a metre and are strict carnivores, the genus is a commitment reserved for very large aquaria or ponds rather than typical home tanks. Conservation assessments are sparse across the genus - 2 species are Not Evaluated, 1 is Data Deficient, and only 1 is confirmed Least Concern.