''Crenuchus spilurus'', the sailfin tetra, is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

belonging to the South American darter family,

Crenuchidae The Crenuchidae, South American darters, are a family of freshwater fish of the order Characiformes. The 12 genera include about 74 species, though several species are undescribed. These fish are relatively small (usually under in standard len ...

. It is found in the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

and

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wo ...

Basins, as well as various river Basins in

the Guianas The Guianas, sometimes called by the Spanish loan-word ''Guayanas'' (''Las Guayanas''), is a region in north-eastern South America which includes the following three territories: * French Guiana, an overseas department and region of France ...

. It is the only member of its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

References

Crenuchidae Tetras Monotypic fish genera Freshwater fish of Brazil Freshwater fish of Colombia Freshwater fish of Peru Fish of the Amazon basin Taxa named by Albert Günther {{Characiformes-stub