Black ghost knifefish

The black ghost knifefish (Apteronotus albifrons) is a nocturnal freshwater fish of the family Apteronotidae, native to the Amazon Basin and other river systems of tropical South America. It has a striking, entirely black, blade-like body with a long undulating anal fin that propels it gracefully forward and backward, plus two white rings on the tail. It is a weakly electric fish, using an electric field to navigate and locate prey in dark waters. Generally peaceful but territorial toward its own kind, it is best kept singly unless the tank is very large. It appreciates dim lighting and hiding places. A spacious aquarium with soft, slightly acidic water, gentle current, and caves or tubes for shelter suits it well. It feeds on worms, insect larvae, and small crustaceans, and will eat very small tankmates, so companions should be medium-sized and peaceful. Sensitive to poor water quality and medications. Breeding in captivity is rare.