About the Black Ghost Knifefish The black ghost knifefish, Apteronotus albifrons, is a South American freshwater fish that grows to 18-20 inches and is characterized by its blade-like appearance due to a lack of dorsal and caudal fins, replaced by a long, wavelike anal fin for maneuverability. It has a white blaze on its nose and two white rings on its tail and uses an electric organ to navigate and find food. These nocturnal and timid fish require a large, dimly lit aquarium with plenty of hiding places. Husbandry & Care Temperament: Peaceful Minimum Tank Size: 75 Gallons (Juvenile), 125 Gallons (Adult) Water Temperature: 75-82 °F Water pH: 6.8-7.8 Social Group: Solitary Diet: Carnivorous; Earthworms, Frozen Bloodworms/Brine Shrimp, High Protein Commercial Pellets Compatible with: Peaceful community fish that cannot be consumed. Geophagus sp., Bristlenose plecos, Silver Dollars, larger catfish of the Corydoradinae family.