Black Ghost Knifefish (Apteronotus albifrons) 6.5cm

The Black Ghost Knifefish is a large nocturnal fish that is a mesmerizing and elegant fish that will steal your heart in no time.

The Black Ghost Knifefish is one of the most popular Knifefish (Apteronotus albifrons). Other common names are Apteronotid eel and Black Knife. An interesting story about this fish is one which is told by South American tribes. It is believed among the tribes that live in the Amazonian jungle, that the souls of the dead inhabit these fish. The common name of this fish, the Ghost Knifefish comes from these stories. They are found throughout the Amazon River and its tributaries, from Venezuela and Paraguay all the way down to the freshwater basins in Peru.

These fish are mainly nocturnal animals and they use electrolocation to navigate dark waters.

Behaviour

Black Ghost Knifefish are tropical freshwater fish from South America. These are nocturnal fish that are most active at night and rest during the day.  As they are most active at night, their eyesight is not well developed, so they hunt and communicate through an electric field.

They are quite shy and not very social preferring their own company – they can become quite aggressive if kept with other Knifefish. After they settle down in the new environment, they will come out from their hiding place during the night and swim mostly near the substrate or foliage and plants.

Tank Conditions

As they are quite a shy fish and will appreciate a tank with many hiding places. Smooth rocks and plants are must-have features for them in your aquarium.  Since this is a scaleless fish so you should provide a fine substrate to avoid injuries – use sand or a very fine gravel mix. The tank should have low lighting with a strong to moderate water current.

Some hobbyists find their fish hiding in the canister filter or tubing. Make sure that when you are setting up the tank, use pre filters or covers any open inlet tubes to avoid surprises.

Since they are scaleless fish and are prone to infections, an UV sterilizer is recommended to avoid complications as it helps to keep the water free of diseases.

Compatibility

These is not an aggressive species toward other tank mates such as peaceful Cichlids, however, it becomes very aggressive when sharing small spaces with the same or similar species.  If you choose to keep these fish together, you will need to allow a minimum of 300 litres per fish.

Even though they are considered semi-aggressive fish, they are perfect for a community aquarium.  The ideal community for this fish is other peaceful similar size fish such as peaceful Cichlids or Catfish. Make sure any tank mates that you add are at least 6 inches in size and are quite peaceful.  The perfect community can be created using peaceful Catfish, Angelfish, large peaceful Cichlids, Discus and Corydoras (will also help keep the aquarium clean). While your Black Ghost Knifefish is growing, you might be able to keep it with smaller size fish such as Tetras, Guppies, Barbs and Rasboras.

Black Ghost Knifefish will start to become aggressive if they are limited to small spaces and if they don’t have enough hiding spots.  They also become quite boisterous if kept with members of the same species or similar species.

Small crustaceans and gastropods (such as shrimps and snails) are not a good match as they are the perfect food for your Black Ghost. They will likely be eaten during night hours.

Don’t keep these fish with other aggressive fish, or fish which are small enough to be considered food.

Feeding

Black Ghost Knifefish are a carnivorous species. In the wild, they feed on insect larvae, juveniles and small fish and worms.  In your tank, this won’t change much and they should be fed with fresh or frozen food such as bloodworms or brine shrimps.  Other alternatives are freeze dried foods such as tubifex worms or crickets. You can also try to feed them pellets or flakes, however, it might take a while for them to get used to this these and they tend to avoid dry food.  It is important to keep a varied and balanced diet to ensure that your fish will receive the right vitamins and minerals for a healthy immune system.

They should be fed daily with an amount of food that they can eat in few minutes. They are nocturnal animals and should be fed in the evening or at night.

Initially, they might struggle to feed. Black Ghosts are quite shy and will take a while to come out from hiding.  Some hobbyists have also been successful to feed their pet from their own hand. This might be something that you want to try, but you will have to be patient. It can take a while to train your fish, but it will be very rewarding.

Care

Black Ghost Knifefish are recommended to more experienced aquarists as they can be challenging to keep.

Ghost Knifefish are freshwater species and can not tolerate any brackish conditions. As the water in their natural environment is quite murky, they are tolerant to a range of water conditions.

One thing to keep in mind for this fish is to never use copper-based medicines as it is very toxic to them.

Since they are scaleless fish and are prone to infections, a UV Sterilizer is  recommended to avoid complications as it helps to keep the water free of diseases.

Knifefish are prone to skin flukes such as the Ich disease. You fish will start to itch and rub themselves around the tank, however with the right treatment they should heal quickly. Raise the temperature up to 30°C if you spot any infection. Higher temperatures interrupt the parasite life cycle preventing reproduction and growth.

See Fish Disease Diagnosis and Treatment at Rebel Pets for help with diagnosing and treating diseases.