''Steatogenys'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of freshwater ray-finned fishes belonging to the family Rhamphichthyidae, the sand kinifefishes. The fishes in this genus are found in the

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

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...

and Essequibo river basins in

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

South America. The widespread and common ''S. elegans'' is found in a wide range of habitats, from the shallow essentially static waters such as floodplain lakes to fast-flowing rivers as deep as . The two remaining species are less common and widespread, with ''A. duidae'' found mainly in small streams running through terra firme forests (forest that does not flood, unlike várzea) and ''S. ocellatus'' among submerged roots and branches in static or slow-flowing blackwater habitats. All three are regularly found among vegetation in floating meadows, a habitat that often contains little oxygen, but they are well-adapted to this. They are well- camouflaged and brown in color with a barred pattern. They resemble the related '' Hypopygus'', but are larger, reaching up to in total length depending on the exact species of ''Steatogenys''. They feed on invertebrates such as aquatic insect larvae and small shrimp.

Taxonomy and species

''Steatogenys'' has traditionally been included in the family

Hypopomidae The Hypopomidae are a family of fishes in the order Gymnotiformes known as the bluntnose knifefish. They may also be called grass or leaf knifefishes. These electric fish are not often eaten, of little commercial importance, rarely kept as aquari ...

, but a comprehensive molecular study from 2015 showed it belongs in

Rhamphichthyidae Sand knifefish are freshwater electric fish of the family Rhamphichthyidae, from freshwater habitats in South America. Just like most part of the members of the Gymnotiformes group, they also have elongated and compressed bodies and electric org ...

, and this has been followed by recent authorities. There are currently three recognized species in this genus: * '' Steatogenys duidae'' ( La Monte, 1929) (Brazil, Venezuela) * '' Steatogenys elegans'' (

Steindachner Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner descri ...

, 1880) (barred knifefish) (Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Venezuela) * '' Steatogenys ocellatus'' Crampton, Thorsen &

Albert Albert may refer to: Companies * Albert Computers, Inc., a computer manufacturer in the 1980s * Albert Czech Republic, a supermarket chain in the Czech Republic * Albert Heijn, a supermarket chain in the Netherlands * Albert Market, a street mar ...

, 2004 (Brazil, Peru)

References

Rhamphichthyidae Knifefish of Brazil Freshwater fish genera Ray-finned fish genera Taxa named by George Albert Boulenger {{gymnotiformes-stub