Apteronotus

The black ghost knifefish, Apteronotus albifrons, is a weakly electric knifefish from the upper half of South America, from Colombia to Paraguay. Usually sold at around 4 inches, it grows to 50 cm and needs a long-term housing plan. Its eyesight is very poor, and it navigates, finds prey and communicates using a weak electric field. In the wild it lives in swiftly flowing streams and rivers over sand.