New World knife fish

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New World knife fish
Green knife fish (Eigenmannia virescens)

Green knife fish ( Eigenmannia virescens )

Subclass : Real bony fish (Teleostei)
Overcohort : Clupeocephala
Cohort : Otomorpha
Sub-cohort : Ostariophysi
Order : New World knife fish
Scientific name
Berg , 1940

The New World knife fish (Gymnotiformes), also called knife eel-like or Nacktaale , are an order of the real bony fish (Teleostei). They occur in the fresh waters of South and Central America .


The animals have an elongated, eel-like body that can be flattened on the side or round in cross-section. It is named after its extra-long anal fin with more than 150 fin rays, which, with its wave-like movements, serves as a forward and backward drive and gives them their knife-like body shape. Ventral fins, pelvic girdle and dorsal fin are missing. A caudal fin is also missing or only very small. The maxillary is toothless. The anus is located in the front half of the body. Gymnotiformes give in case of danger no shock substance from.

Way of life

All species of the New World knife fish are active at night or at dawn and have an electrical organ for orientation. In the largest species, the electric eels ( Electrophorus sp.), Which can grow to a maximum of two meters in length , the voltage generated is so high that they can kill their prey with it. Most species are specialized insect larvae eaters that occur in very different biotopes. Almost all knife eels do not care for their brood.

Catfish such as the tiger spatula are close relatives of the New World knife fish.

External system

The gymnotiformes among the Ostariophysi , which also include Cyprinids (Cypriniformes), the catfish-like (Siluriformes), and especially from the fighting dogs known Characins (Characiformes) belong. Their phylogenetic relationships are shown in the following cladogram :


 Herring-like (Clupeiformes)




 Sandfish (Gonorynchiformes)


 Carp-like (Cypriniformes)


 Tetras (Characiformes)


 New World Knifefish (Gymnotiformes)


 Catfish (Siluriformes)

Template: Klade / Maintenance / Style

Internal system

There are two suborders, two superfamilies, five families, 30 genera and about 160 species.

  • Subordination Gymnotoidei; Body cylindrical, 31 to 51 vertebrae in front of the caudal spine (more than 100 in the electric eel).
  • Subordination Sternopygoidei; Body mostly laterally flattened (rarely also cylindrical), 12 to 26 vertebrae in front of the caudal spine.


Web links

Commons : New World Knifefish  - Collection of images, videos and audio files