Black Ghost Knife (Apteronotus albifrons)

Most weakly electric fish generate their field with an electric organ built from modified muscle tissue, but black ghost knives are part of a small group where the organ is neurogenic instead — built from modified nerve tissue rather than muscle. That electric field lets it navigate and hunt in complete darkness, and it can swim backward with the same fluid control as forward thanks to a long undulating fin running the length of the body.

Care level: Moderate · Temperament: Peaceful, territorial with own kind · Max size: ~18" · Min tank: 100+ gal (adult) · Diet: Carnivore, live/frozen foods