Arhinolemur is a genus of South American characiform fish - the order that also contains tetras, piranhas, and pacus - grouped in the atlas among the region's non-tetra characins rather than the true piranhas themselves. The three atlas species range widely in size, from roughly 9.5 in up to 30 in, and carry long-established Brazilian and Rio de la Plata common names - piau-gaiero, timbure, and boga - names traditionally used for elongate, silvery river characins of this kind. The genus is native to the Parana-Plata drainage, recorded here across Brazil, Argentina, Paraguay, and Uruguay.
Boga in particular is a well-known name among Rio de la Plata anglers and river communities, where fish of this general type are an established food and sport catch rather than an aquarium staple - their size alone puts them outside typical home tanks. Conservation status is uneven across the genus: one species is Endangered, one Least Concern, and one not yet formally assessed, which fits the broader pattern of pressure on Parana-Plata basin fish from damming and river regulation that has fragmented migratory routes across the region.