Black Ghost Knife Fish

Black Ghost Knife Fish (Apteronotus albifrons) is one of the most iconic and mesmerizing freshwater fish in the hobby. The jet-black, blade-shaped body with distinctive white rings at the tail and a white stripe along the nose creates a ghost-like profile that moves through the water in an extraordinary undulating motion — propelled by the long anal fin wave rather than typical fish tail movement. It generates a weak electric field to navigate in complete darkness.

Feeding & Care Tip: Hikari Micro Pellets soaked and Hikari Frozen or Freeze-Dried Bloodworms make excellent staples — feed after lights dim. Supplement with Hikari Frozen or Freeze-Dried Baby Brine Shrimp and Hikari Frozen or Freeze-Dried Tubifex Worms. Black Ghost Knife Fish are slow, deliberate feeders; target-feed to ensure they receive adequate food in community settings.

Native to the fast-flowing, blackwater rivers of the Amazon basin — Brazil, Peru, and surrounding areas. Inhabits clear to blackwater rivers with sandy substrate and abundant submerged wood. Soft, slightly acidic water with tannin additions produces the most relaxed and well-colored fish. A large aquarium is important — this species grows to 20 inches.

Keep singly or with large, peaceful fish. Territorial toward its own kind in smaller aquariums. Sensitive to water quality — high nitrates cause stress and disease. Regular large partial water changes are important. Do not keep with other weakly electric fish — the electric field interference causes significant stress.

Knife fish generate a weak electric field to navigate and communicate — keep only one species of weakly electric fish per tank, as the electric fields of multiple fish interfere with each other causing stress. Provide PVC pipes or caves large enough for the fish to rest inside completely. Dimly lit aquariums with plenty of cover replicate their natural blackwater habitat.

Care & Ideal Parameters