Anodus is a genus of elongate, silvery characiform fish native to major South American river systems - the atlas's 2 species, Anodus elongatus and Anodus orinocensis, range across the Amazon and Orinoco drainages in Brazil, Colombia, Ecuador, Peru, and Venezuela. Adults grow to a substantial 11–12 in, with a slim, compressed, torpedo-like body built for schooling in open water rather than hugging cover, and a small mouth suited to grazing algae and fine organic matter rather than active predation.
Anodus elongatus, known locally as charuto ('cigar,' for its slim cylindrical shape), has some regional importance as a food and bait fish in parts of its Amazonian range, but neither Anodus species has an established place in the aquarium hobby - their size and open-water schooling habits make them impractical home-aquarium fish. Both atlas species are assessed as Least Concern, consistent with a genus that ranges widely across large, still relatively healthy river systems.