''Steatogenys'' is a

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 ...

of gymnotiform knifefishes 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 ...

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 ...

and

Essequibo Essequibo is the largest traditional region of Guyana but not an administrative region of Guyana today. It may also refer to: * Essequibo River, the largest river in Guyana * Essequibo (colony), a former Dutch colony in what is now Guyana; * Esseq ...

river basins in

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

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 Blackwater or Black Water may refer to: Health and ecology * Blackwater (coal), liquid waste from coal preparation * Blackwater (waste), wastewater containing feces, urine, and flushwater from flush toilets * Blackwater fever, an acute kidney disea ...

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 Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...

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 aquar ...

, 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 ''Steatogenys'' is a genus of gymnotiform knifefishes found in the Amazon, Orinoco and Essequibo river basins in tropical South America. The widespread and common ''S. elegans'' is found in a wide range of habitats, from the shallow essentially ...

'' ( La Monte, 1929) * ''

Steatogenys elegans ''Steatogenys elegans'', the barred knifefish, is a species of Hypopomidae (bluntnose knifefishes) found in tropical South America. It is the type species of its genus. It is an electric fish found in a wide range of freshwater habitats in the ...

'' (

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 describ ...

, 1880) (Barred knifefish) * ''

Steatogenys ocellatus ''Steatogenys'' is a genus of gymnotiform knifefishes found in the Amazon, Orinoco and Essequibo river basins in tropical South America. The widespread and common ''S. elegans'' is found in a wide range of habitats, from the shallow essentially ...

'' Crampton, Thorsen &

Albert Albert may refer to: Companies * Albert (supermarket), a supermarket chain in the Czech Republic * Albert Heijn, a supermarket chain in the Netherlands * Albert Market, a street market in The Gambia * Albert Productions, a record label * Alber ...

, 2004

References

Hypopomidae Freshwater fish of South America Freshwater fish genera Ray-finned fish genera Taxa named by George Albert Boulenger {{gymnotiformes-stub