Gnathocharax

Gnathocharax, is a monospecific genus of freshwater ray-finned fish belonging to the family Acestrorhynchidae, which includes the freshwater barracudas and the biting tetras. The only species in the genus is Gnathocharax steindachneri,^[3] also known as the arowana tetra.^[4] This is fish found in tropical freshwater habitats in the Orinoco and Amazon Basins of South America.

Gnathocharax
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Characiformes
Family:	Acestrorhynchidae
Subfamily:	Heterocharacinae
Genus:	Gnathocharax Fowler, 1913[2]
Species:	G. steindachneri
Binomial name
Gnathocharax steindachneri Fowler, 1913[3]

Taxonomy

Ganthocharax was first proposed as a genus in 1913 by the American zoologist Henry Weed Fowler when he described its only species, G. steindachneri.^[2] Fowler gave the type locality of this species as the Igarapé de Candelaria, a tributary of the Rio Madeira and about 2 miles (3.2 km) distant, at 8°45'S, 63°54'W, in Brazil.^[3] This taxon was formerly classified in the family Characidae but is now classified within the subfamily Heterocharacinae, the small biting tetras, of the family Acestrorhynchidae,^[2] within the suborder Characoidei of the order Characiformes.^[5]

Etymology

Ganthocharax combines gnáthos, meaning "jaw" in Greek, an allusion to the angled elongated maxilla, with charax, meaning a "palisade". Charax is a reference to its dense, sharp teeth and is a common element in the scientific names of characins. The specific name honours Franz Steindachner, the Austrian ichthyologist.^[6]

Description

Gnathocharax has a maximum standard length of 5 cm (2.0 in).^[7] This taxon has a thin, laterally compressed body. Both jaws have prominent, protruding teeth and the mouth points upwards. The background colour is silvery witha greenish iridescence with a black blotch with red spots on its anterior and posterior margins on the caudal peduncle. There is a red crescent around the eyes and there is a scattering of small black spots on the otherwise transparent fins.^[8]

Distribution

Gnathocharax is found un the drainages of the Amazon and Orinoco Rivers and has been recorded from Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela.^[1]