Knifefish refers to several knife-shaped fishes: The order Gymnotiformes of knifefishes. The family Notopteridae of featherbacks. The family Sternopygidae of glass knifefishes. Four other fishes not in any of the above: Grey knifefish, Bathystethus cultratus. Blue knifefish, Labracoglossa nitida. Collared knifefish or Finscale razorfish, Cymolutes torquatus. Jack-knifefish, Equetus lanceolatus.… (More on Knifefish)