Care Level: Advanced

Temperament: Peaceful

Live Plant Safe: Yes

General Description: The Black Ghost Knife has a vast distribution across the deep and murky waters of the Amazon Basin in South America. One of the most admired oddball fishes in the hobby, the Black ghost knife has a thin and long blade-shaped body that is entirely black except for two white bands at the base of its body and a white line that starts at the front of its face and runs along it dorsally to the base of its body. Black ghost knife do not have dorsal or caudal fins; they only possess a modified anal fin and a pair of pectoral fins in which they use for movement. This “flowy-looking” modified anal fin allows the Black ghost knife to not only move in typical fish fashion but also in reverse with incredible ease. Given the natural environment in which they originate from, Black ghost knife have evolved with extremely poor eyesight. They rely on an electrical organ at the base of their body that omits weak electrical pulses, and electroreceptor cells embedded within their skin, in order to locate food, communicate with other Black ghost knife fish and to navigate an even completely dark environment. There are so many unique qualities that Black ghost knife fish have that catch the attention of hobbyists, however many individuals end up in less than suitable aquarium conditions. First, because this species has adapted to living in darkness in addition to it being nocturnal by nature, Black ghost knife are sensitive to bright lighting and will remain withdrawn during the day typically in this case. Lighting should be dim, or food items will otherwise need to be supplemented at lights out when this species will forage. Second, Black ghost knife are scaleless which makes them more susceptible to disease, and sensitive to medications, salt and deteriorating water parameters. Extremely clean water needs to be maintained for the overall health of this fish to particularly avoid fungal infections. And third, while most Black ghost knife offered for sale are cute and small 2 to 3″ juveniles, this species can grow up to 20″ as an adult requiring an aquarium with a large length and width footprint. Black ghost knife are predators by nature, and will leave most tank mates alone if they are not small enough to be mistaken for a meal. Only one Black ghost knife should be kept per aquarium, as they are aggressive toward conspecifics. Black ghost knife fish would likely show aggression toward other “electrical field producing” fish including Elephant Nose (Gnathonemus petersii) and Brown Ghost Knife (Apteronotus leptorhynchus).

Diet Requirements: Black ghost knife are carnivores, and can be finicky at first but with the proper environment, will readily accept various freeze-dried and frozen foods including bloodworms, mysis shrimp and other mixed freshwater preparations. Live blackworms as an occasional treat will be appreciated. Variety is the spice of life in order to maintain color, immune function and longevity of your fish. Options will change with the size of your Black ghost knife fish.

Care Requirements: An established minimum 75 gallon aquarium is ideal for a juvenile Black ghost knife. The tank will need to be upgraded accordingly as this fish matures and grows. Black ghost knife should be added only into a biologically established aquarium, as they cannot tolerate nitrite or ammonia. Additionally, Black ghost knife are very sensitive to deteriorating water parameters, so weekly water changes should be done to keep water chemistry pristine (Nitrates < 15 ppm) and the aquarium should be equipped with efficient filtration. Aquascape the aquarium with smooth rocks, driftwood or branches, floating plants to dim the lighting, and live plants for cover. Anubias plants will thrive in dimmer lighting conditions. Those that keep any knife fish will also put a couple of plastic tubes, or PVC pipe, in the aquarium for knife fish to shelter inside of. Black ghost knife are relatively peaceful, though they can exhibit some territoriality toward tank mates that encroach on their space. Their poor eye sight and dietary needs should be taken into consideration when choosing tank mates, in addition to their innate predatory behavior. Avoid overly competitive and aggressive fish that would stress your Black ghost knife, and stick with somewhat docile but larger growing species such as various catfish, tetra, gourami, rainbowfish, angelfish, bala shark, and certain cichlids. Black ghost knife should not be kept with any invertebrates. Recommended water conditions, 72-82° F, KH 5-10, pH 6.0-8.0.

Purchase Size: Small: 2” to 3”; Medium: 4” to 6”; Large: 7” to 9”; XLarge: 10″ or larger. 

Note: Your item may not look identical to the image provided due to variation within species. Purchase sizes are approximate.