Galeocharax is a genus of predatory characins in the family Characidae - the wolf tetras, named for their elongate, torpedo-shaped bodies and mouths lined with conspicuous, backward-curving teeth. The atlas's 2 species range very widely across South America, recorded from Brazil, Argentina, Bolivia, Colombia, Ecuador, French Guiana, Paraguay, and Peru, and typically hunt smaller fish in open water in rivers and floodplain lakes. They are large for tetras, running 25 to over 12 in.
Neither the wolf tetra (Galeocharax gulo) nor the humpback characin (G. humeralis) is a mainstream aquarium fish - their size and predatory habits limit them to large specialist setups rather than typical community tanks, and they turn up mostly through the export trade for South American predatory fish rather than as deliberately bred stock. Both species are Least Concern, consistent with their broad range across multiple major river systems.