Black Ghost Knife Fish

The Black Ghost Knife Fish is one of the most exotic and captivating fish available to aquarists. Named for their striking black coloration with two white rings on the tail and a white blaze on the nose, these fish are enveloped in South American folklore that claims they house the souls of the departed. In reality, they are fascinating electrical fish that generate weak electric fields to navigate in complete darkness and locate prey. They have no dorsal or caudal fins, instead using an elongated anal fin that runs the length of their body to swim with a graceful, undulating motion that resembles a knife moving through water. Black Ghost Knife Fish are intelligent and can recognize their owners, even learning to take food from hands. Their impressive size, unique appearance, and electrical abilities make them a showpiece for very large aquariums, though their specific care requirements and eventual size make them suitable only for experienced aquarists with substantial tank space.

Care Requirements

Tank Setup

Black Ghost Knife Fish require a very large aquarium of at least 100 gallons due to their eventual size of up to 20 inches. They need soft, sandy substrate and numerous hiding spots including PVC pipes, driftwood caves, and rock formations. Dim lighting is essential as they are nocturnal. Excellent filtration is critical for maintaining water quality in such a large tank.

Water Quality

• Temperature: 73-80°F (23-27°C)
• pH: 6.0-8.0
• Water Hardness: Soft to moderate, 2-15 dGH
• Ammonia/Nitrite: 0 ppm
• Nitrate: <20 ppm

Feeding

These carnivores prefer live or frozen foods such as bloodworms, krill, and brine shrimp. Larger specimens may accept pellets and can handle small feeder fish, though frozen alternatives are safer to avoid disease. Feed in the evening when they are most active. They have large appetites appropriate for their size.

Behavior & Compatibility

Black Ghost Knife Fish are generally peaceful but their large size and predatory nature means small tank mates will be eaten. They should be housed with other large, peaceful fish such as Silver Dollars or large catfish. They can be territorial toward their own kind and other knifefish. They are nocturnal and most active at night.

Tips for Success

• Provide hiding spots where they can retreat during the day; PVC pipes work well
• They are scaleless and sensitive to medications; treat carefully
• Long-lived fish that requires long-term commitment; can live 10-15 years
• Use soft substrate to protect their elongated anal fin
• They are intelligent and may learn to recognize their owners
• Dim lighting and plenty of hiding spots help them feel secure
• Excellent filtration is essential for maintaining water quality in their large tanks