The black ghost knifefish, Apteronotus albifrons, is a tropical fish belonging to the ghost knifefish family (Apteronotiae). They originate in South America in the Amazon Basin in Peru and from Venezuela through Paraguay in the Paraná Rivers. They are becoming popular in aquaria. The fish is all black except for two white rings on its tail, and a white blaze on its nose, which can occasionally extend into a stripe down its back. It moves mainly by undulating a long fin on its underside. It will grow to a maximum length of 25 inches (60 centimeters).