Notopteridae: Featherbacks and Knifefishes

Gymnotiforms, the electric knifefishes from South and Central America. Although their manner of swimming is similar and they are superficially similar in appearance, the two groups are not closely related.

There are ten species of Notopteridae:

  • Genus Chitala
    • Chitala blanci (royal knifefish or Indochina featherback)
    • Chitala borneensis (Indonesian featherback)
    • Chitala chitala (Indian featherback)
    • Chitala hypselonotus
    • Chitala lopis (giant featherback)
    • Chitala ornata (clown featherback or clown knifefish)
  • Genus Notopterus Lacépède
    • Notopterus notopterus (bronze featherback)
  • Genus Papyrocranus
    • Papyrocranus afer (reticulated knifefish)
    • Papyrocranus congoensis
  • Genus Xenomystus
    • Xenomystus nigri (African knifefish)

Knifefish have slender, elongated, bodies, giving them a knife-like appearance. The caudal fin is small and fused with the anal fin, which runs most of the length of the body. Where present, the dorsal fin is small and narrow, giving rise to the common name of "featherback."

The fish swims by holding its body rigid and rippling the anal fin to propel itself forward or backwards.

Notopterids have specialized swim bladders. The organ extends throughout the body and even into the fins in some cases. Although the swim bladder is not highly vascularised, it can absorb oxygen from air and also functions to produce sound by squeezing air through a narrow passage into the pharynx.

At least some species prepare nests and guard the eggs until they hatch.


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Clown knife fish (Notopterus chitala) can grow to 36 – 40 inches

The Clown Knife Fish has to be one of the strangest looking freshwater tropical fish available in the hobby. With its elongated head, huge underslung jaw and humped back, it definitely doesn’t appeal to all. But for all its odd looks, these fish have great personalities and are amazing to watch gliding around the tank at night.