Animal-World > Freshwater Fish > Aquarium Knifefish | Knifefishes

Knifefish

Orders: Osteoglossiforms and Gymnotiformes
Clown Knifefish - (albino)Chitala ornata Photo © Animal-World: Courtesy Pavaphon Supanantananont

   The Knifefishes sport an unusual, beautiful, and yes... you guessed it! A knife type shape!

   'Knifefish' or 'Knife Fish" is a visually descriptive term for these fish. Some can get rather large, but all in all they make an attractive addition to a community tank or a splendid show fish in a specialty tank.

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   True to their name, the Knifefish have a long, tapered, and laterally compressed body shape. This along with a continually moving fin on their underside, likens them to a household knife. This fin is continuously moving with an undulating motion which they use to swim about. Their graceful movements are shown to best advantage in a longer aquarium.

See more information on Knifefish below:
Description and Care & Feeding

Knifefish
Aba Knife	African Knife Fish
Gymnarchus niloticus	Xenomystus nigri
Black Ghost Knife Fish	Centipede Knifefish
Apteronotus albifrons	Steatogenys duidae
Clown Knifefish	Elegant Knifefish
Chitala ornata	Steatogenys elegans
Featherfin Knifefish	Glass Knife Fish
Notopterus notopterus	Eigenmannia virescens
Reticulate Knifefish	Zebra Knifefish
Papyrocranus afer	Gymnotus pedanopterus

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Osteoglossiforms:

• This order includes the family Notopteridae, called the Featherbacks or Featherfin Knifefishes and are found in Southeast Asia and Africa.
• They are characterized by having a continuous fin along the underside formed by a joining of the caudal and anal fin, and by either not having a dorsal fin or having a very small one. These fish can be quite large, ranging in size from about 8 inches (20 cm) up to about 5 feet (152 cm) though most are in about the 3 to 4 foot (91 - 122 cm) size.
• Some of the other families in this order include True Bony Fishes such as the Arowanas and Butterflyfish, as well as the Mormyridae family of Elephantfishes.

Gymnotiformes:

• This order includes six families; the family Sternopygidae called the Glass Knifefishes, the family Rhamphichthyidae called the Sand Knifefishes, the family Hypopomidae, the family Gymnotidae called the Naked-back Knifefishes, and the family Apteronotidae called the Ghost knifefishes
• These fish are found in Central and South America. Some of their characteristics are an eel-like body that's either flattened or rounded, no dorsal fin, an extremely long anal fin starting near the pectoral fin area which can move in an undulating forward or backward motion, no caudal fin or a greatly reduced one, and they have electric organs present.
• The electric organs allow them to generate a very weak electric field around their body which helps them identify objects other than water. This field helps them with their spatial orientation and to navigate, along with helping them detect food. Males use an electric 'stereotyped' communication to court females.
• Some of these fish inhabit quiet lakes or lagoons while others live in main river channels. Others, as some of those in the family Sternopygidae, the genus Gymnotus, live along river banks or on flood plains among roots or plant matter. Some species even like to burrow into substrate. Largely nocturnal they become active at night and are predators that eat insects, crustaceans, and other fish. They are sensitive to some fish medications such as copper and those containing formalin.

Perciformes - 'perch-like' fishes:

• Some others also called 'Knifefish' in their common name, but classified in the order Perciformes (the 'perch-like' fishes) are the Grey knifefish Bathystethus cultratus, Blue knifefish Labracoglossa nitida, Collared knifefish or Finscale razorfish Cymolutes torquatus, Jack-knifefishEquetus lanceolatus.
• These fish are not included in this category, rather they will be included in the "Perches and Perch-like fish" category.

Care and feeding:
   In general Knifefish are shy secretive fish that will avoid the light, so provide them with hiding places such as hollow logs, rocks, and caves. Most are nocturnal, eating and being more active at night. Though usually peaceful with similar sized tank mates they can be aggressive eaters, smaller fish will not do well with them. Some are also territorial and will quarrel with others of their own species. They are great jumpers so be sure you have a tight fitting top on the aquarium.
   For success in keeping Knifefish pay special attention to their feeding needs. Being nocturnal they can be fed after you turn out the lights, just be sure to remove any uneaten foods in the morning to maintain good water quality and prevent an additional load on your filtration. Knifefish live on average 3 to 7 years, with some species living over 10 years.

Buy Black Ghost Knifefish
From LiveAquaria.com

For more Information on keeping freshwater fish see:
Guide to a Happy, Healthy Freshwater Aquarium

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