Knifefish may refer to several knife-shaped fishes: *The Neotropical or weakly electric knifefishes, order

Gymnotiformes The Gymnotiformes are an order of teleost bony fishes commonly known as Neotropical knifefish or South American knifefish. They have long bodies and swim using undulations of their elongated anal fin. Found almost exclusively in fresh water (the ...

, containing five families: **Family Gymnotidae (banded knifefishes and the electric eel) **Family

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 o ...

(sand knifefishes) **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 aqu ...

(bluntnose knifefishes) **Family Sternopygidae (glass and rat-tail knifefishes) **Family

Apteronotidae The ghost knifefishes are a family, Apteronotidae, of ray-finned fishes in the order Gymnotiformes. These fish are native to Panama and South America. They inhabit a wide range of freshwater habitats, but more than half the species in the family ...

(ghost knifefishes) *The featherbacks, family

Notopteridae The family Notopteridae contains 10 species of osteoglossiform (bony-tongued) fishes, commonly known as featherbacks and knifefishes. These fishes live in freshwater or brackish environments in Africa and South and Southeast Asia. With the denot ...

. *The aba, ''

Gymnarchus niloticus ''Gymnarchus niloticus'' – commonly known as the ''aba'', ''aba aba'', frankfish, freshwater rat-tail, ''poisson-cheval'', or African knifefish – is an electric fish, and the only species in the genus ''Gymnarchus'' and the family Gymnarchid ...

'' *Four other unrelated fish species not in any of the above families: **

Grey knifefish The grey knifefish (''Bathystethus cultratus'') is a species of sea chub native to the Pacific Ocean from Australia to New Zealand and the Kermadec Islands. This species is a plankton Plankton are the diverse collection of organisms found ...

, ''Bathystethus cultratus''. **

Blue knifefish The blue knifefish (''Labracoglossa nitida'') is a species of marine ray-finned fish, a member of the subfamily Scorpidinae of the sea chub family Kyphosidae. It is native to the Pacific Ocean waters off eastern Australia over to New Zealand, ...

, ''Labracoglossa nitida''. **Collared knifefish or finscale razorfish, ''Cymolutes torquatus''. **

Jack-knifefish The jack-knifefish (''Equetus lanceolatus'') is a species of fish in the family Sciaenidae, the drums and croakers. It is native to the western Atlantic Ocean, where its distribution extends along the eastern coasts of the Americas from the Carol ...

, ''Equetus lanceolatus''.

See also