Cynopotamus is a genus of predatory South American characins, often called dogtooth tetras for the prominent canine-like teeth in their protruding lower jaw, used to slash and seize smaller fish. They are slim, silvery, laterally compressed characins allied with the pike characins of Acestrorhynchus, and the atlas's 12 species are recorded across an unusually wide swath of South American lowland rivers, from the Amazon, Orinoco, and Guiana drainages (Brazil, Colombia, Venezuela, Peru, Bolivia, Guyana, French Guiana) down to Argentina's Paraná-La Plata system, with the largest species reaching about 15.5 in.
Cynopotamus is mostly of scientific and local-fisheries interest rather than aquarium interest; its predatory habits and size make it impractical for typical home tanks, and it rarely appears in the ornamental trade. In parts of its range, such as Argentina, it is known locally by vernacular names like cachana and taken in small-scale fisheries. Conservation data lean Least Concern (6) and Not Evaluated (5) with a single Vulnerable species, more a sign of limited targeted survey work across such a wide-ranging riverine predator than evidence of population decline.