Glass knifefish

Glass knifefishes are fishes in the family Sternopygidae in the order Gymnotiformes. Species are also known as rattail knifefishes.[1]

Glass knifefishes Temporal range: Late Miocene–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Eigenmannia virescens
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Gymnotiformes
Suborder:	Sternopygoidei
Superfamily:	Apteronotoidea
Family:	Sternopygidae Cope, 1871

These fishes inhabit freshwater streams and rivers in Panama and South America.[1] Many sternopygid species are specialized for life in the deep (more than 20 m or 66 ft) swiftly moving waters of large river channels, like that of the Amazon and its major tributaries[2] where they have been observed swimming vertically.[3] Sternopygus species inhabit both streams and rivers.[4]

Many species are highly compressed laterally and translucent in life.[4] These fish have villiform (brush-like) teeth on the upper and lower jaws. The snout is relatively short. The eyes are relatively large, with a diameter equal to or greater than the distance between nares. The anal fin originates at the isthmus (the strip of flesh on the ventral surface between the gill covers). The maximum length is 140 cm (55 in) in Sternopygus macrurus.

Eigenmannia vicentespelaea is the only cave-dwelling gymnotiform. Humboldtichthys kirschbaumi (formerly genus Ellisella) from Upper Miocene of Bolivia is the only fossil gymnotiform.[1]

These fish have a tone-like electric organ discharge (EOD) that occurs monophasically.

Some of these species are aquarium fishes.

Genera

There are 30 living species of glass knifefish, grouped into six genera:[5]

• Archolaemus
• Distocyclus
• Eigenmannia
• †Humboldtichthys (fossil, Upper Miocene)
• Japigny
• Rhabdolichops
• Sternopygus

References

1. Nelson, Joseph, S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 978-0-471-25031-9.
2. Crampton, W.G.R., Hulen, K., & Albert, J.S. (2004). "Sternopygus branco, a new species of Neotropical electric fish (Gymnotiformes: Sternopygidae) from the lowland Amazon basin, with descriptions of ecology and electric organ discharges." Copeia 2004(2): 244-258.
3. Kate Humble (2005). Amazon Abyss (TV-Series). BBC.
4. Froese, Rainer, and Daniel Pauly, eds. (2007). "Sternopygidae" in FishBase. Apr 2007 version.
5. Froese, Rainer, and Daniel Pauly, eds. (2011). "Sternopygidae" in FishBase. December 2011 version.

Further reading

• Albert, J.S. 2003. Family Sternopygidae. Pp 493–497 in R.E. Reis, S.O. Kullander & C.J. Ferraris, Jr. (eds). Checklist of the Freshwater Fishes of South and Central America. Edipucrs, Porto Alegre, 735p.
• Meunier, F.J.; Jégu, M.; Keith, P. 2011: A new genus and species of neotropical electric fish, Japigny kirschbaum (Gymnotiformes: Sternopygidae), from French Guiana. Cybium, 35(1): 47–53. ISSN 0399-0974 abstract only seen