Knifefish

Knifefish may refer to several knife-shaped fishes:
 * The Neotropical or weakly electric knifefishes, order Gymnotiformes, containing five families:
 * Family Gymnotidae (banded knifefishes and the electric eel)
 * Family Rhamphichthyidae (sand knifefishes)
 * Family Hypopomidae (bluntnose knifefishes)
 * Family Sternopygidae (glass and rat-tail knifefishes)
 * Family Apteronotidae (ghost knifefishes)
 * The featherbacks, family Notopteridae.
 * The aba, Gymnarchus niloticus
 * Four other unrelated fish species not in any of the above families:
 * Grey knifefish, Bathystethus cultratus.
 * Blue knifefish, Labracoglossa nitida.
 * Collared knifefish or finscale razorfish, Cymolutes torquatus.
 * Jack-knifefish, Equetus lanceolatus.