Black Ghost Knife Fish (Apteronotus albifrons): Care Guide

Common Name(s)Black Ghost Knife Fish
Scientific NameApteronotus albifrons
OriginSouth America
Temperature73-82°F (23-28°C)
Size19 in (50 cm)
Minimum Tank Size100 gallons
Food & DietCarnivorous diet (prefers live fish food)
Lifespan15 years
Water pH6.0-8.0
Tank MatesSouth American Cichlids, Mono Sebae, peaceful Catfish species, Corydoras, and Discus.
BreedingSpawn eggs in rocky substrate
DiseaseMay be susceptible to Ich and fungal infections.

Black Ghost Knife Fish (Apteronotus albifrons) is an interesting aquarium fish that originates in South America. They have an long body that is shaped like a knife. They will grow to a significant size, but they are agile fish that are able to maneuver around objects in the tank. They will live a long time as well, if they are well taken care of. As a nocturnal fish, they will feed primarily at night. These fish are known to have poor vision, but they possess an electrical organ, which helps them locate their food.

These fish are fond in tropical waters of the Amazon River Basin of South America. Among some of the tribes of the Amazonian jungles, it is believed that the souls of the deceased inhabit these fish.

Black Ghost Knife Fish Care

Black Ghost Knife Fish are moderately difficult fish to take care of. They are a fish that grow to a significant size, and they do not tolerate poor water quality. Therefore, a proper tank setup and regular maintenance is important. Of course, these fish aren’t reserved for experts only. However, in comparison to other hardy fish in the aquarium hobby, these fish require a little more attention and care.

Another factor to consider is that these fish do not have scales. This makes them susceptible to injuries and infections. Therefore, it may be wise to install a UV sterilizer in the tank. One thing to remember about these fish is that copper-based treatments are extremely poisonous to them. If copper-based treatment is administered, the fish may begin to scratch and rub themselves around the tank. There are other proper methods of treating an infection for these fish. If treated early, and the temperature is increased to about 86°F, there is a good chance that they will be able to fight off the infection.

Black Ghost Knife Fish
Black Ghost Knife Fish (Apteronotus albifrons)


Black Ghost Knife fish are South American tropical freshwater fish. These fish are nocturnal, meaning that they are most active at night and sleep throughout the day. Because they are most energetic and have poor eyesight, they search and converse using an electromagnetic field.

They are shy and introverted, preferring to be alone. If maintained with other Knife fish, they can become violent. They will emerge from their hiding location throughout the night after settling into the new habitat and swim largely towards the base of leaves and plants.


Apart from two white rings on its tail and a white stripe on its nose that often runs along its back, the Black Ghost Knife fish is completely black. It has no caudal or dorsal fins, hence it has the appearance of a knife.

There are no scales on this Knife fish species. As a result, because it lacks the added protection provided by scales, this fish is extremely vulnerable to water conditions and illnesses. Electric signals can be sent and received by Black Ghost Knife fish. An organ in the tail is responsible for generating energy.


The Amazon River and its tributaries are home to the Black Ghost Knife fish, which may be found from Venezuela and Paraguay down to Peru’s freshwater basins. There are plenty of nooks and crannies to hide in these waters, which are densely forested. With poor lighting and considerable water currents, the waters are normally extremely muddy.

The water would also be warm, with a pH that was close to neutral. Because they have no scales, the base underlying them would be soft sand that would not scrape.


The tank’s water temperature must be maintained at a constant level between 73-82°F (23-28°C). It is important to note that they are freshwater fish that cannot survive in brackish water. This river-dwelling species prefers water with a moderate to high current.

Water pH

The pH range for the Black Ghost Knife fish is 6.0 to 8.0, with water hardness ranging from 5 to 19 dGH.

Black Ghost Knife Fish Size

One of the largest ghost knife fish species is the black ghost knife fish. The fish are well-known for their high development rates. The black ghost knife fish grows to be 19 in (50 cm) long on average, although some grow to be 23 in (60 cm) long.

Tank Size

One black ghost knife fish requires at least tank capacity of 100 gallons. These fish can develop to be fairly huge, so you’ll need a tank that can hold them. Maintaining a fish of this size in a small tank will not only make them more aggressive, but it will also harm their condition. All other care elements are founded on the basis of having the proper tank size. You could have the highest aquatic environment in the world, but it won’t make any difference if the tank is too tiny.                          

Food & Diet

Black ghost knife fish have a diet that is quite close to what they eat in their native habitat. Black Ghost Knife fish, unlike several other species, are notoriously difficult to switching to flake or pellet feeds. As a result, we prefer to give people what they desire. The black ghost knife fish that have survived the longest have been fed a more protein-rich and natural diet, according to our observations. Any of your favorite live or frozen meals will suffice. Owners frequently utilize bloodworms, prawns, brine shrimp, and tubifex.


The Black Ghost Knife fish lives for a very long time. It can survive for up to 15 years if properly looked for. With its no scale form, people assume it to be one of the short-lived tank fish, thus this is a strong season.

Care Guide for Black Ghost Knifefish – Aquarium Co-Op

Tank Mates for Black Ghost Knife Fish

There are a variety of black ghost knife fish tank mates to choose from. This is due to the fact that this species prefers to keep to itself and does not use its size to bully others.

As long as the fish aren’t too little, almost any peaceful freshwater fish can be partnered with your black ghost knife fish. Small fish such as Celestial Pearl Danios or Green Neon Tetras have been used by certain owners, but this coupling is only possible while the black ghost knife fish is still young.

Are Black Ghost Knife Fish Aggressive?

Black Ghost Knife Fish are normally peaceful fish, but if your tank is too small, they can turn aggressive with other fish of their species. You can keep many Black Ghost Knife fish, but you’ll need a big aquarium (at least 100 gallons) to do it securely.

Compatible Tank Mates

South American Cichlids, Mono Sebae, peaceful Catfish species, Corydoras, and Discus are all good tank mates for the Black Ghost Knife fish. The Corydoras make a wonderful tank mate because, in spite to being fantastic mates for your Black Ghost Knife fish, they will also assist maintain a clean tank.

Incompatible Tank Mates

Examples of incompatible tank mates are Shrimp, Oscar fish, Rainbow shark, Gold fish, Tetras, Guppies, Barbs, and Rasboras. Don’t keep these fishes with black ghost knife fish as they are small enough to be considered food.

Tank Setup

Because the fish is accustomed to living in darkness, it is better to provide the medium-bright, muted lighting. Consider what other fish in your community tank demand before installing this type of lighting.

Add a combination of sand and gravel to the tank’s bottom to mimic their native habitat’s environment. Logs, wood, and pebbles in the tank will provide great hiding and lounging locations for your Black Ghost Knife Fish. Keep them to the sides of the aquarium to allow the fish to move around freely.

Do Black Ghost Knife Fish require a hiding tube?

Yes, Black Ghost Knife fish requires a hiding tube. Aquatic species, Black Ghost Knife fish cannot survive brackish conditions. Fish can be found lurking in the canister filter or tubing by certain enthusiasts. To avoid unpleasant situations, use pre-filters or seal any exposed inlet tubes of the aquarium filter when building the tank.

What do Black Ghost Knife Fish habitat look like in the wild?

The Black Ghost Knife fish is a type of freshwater fish that originated in South America. In a tropical climate, the black ghost knife fish (Apteronotus albifrons) thrives in fast-moving, sandy-floor creeks.

Even during wet seasons, several species migrate to flooded forests to breed. While most species prefer tranquil water with plenty of flora, glass knives prefer deep river systems with strong currents.

Black Ghost Knife Fish Breeding

In a home aquarium, breeding the Black Ghost Knife is nearly impossible. The major reason for this is the enormous tank size requirements, which will need to be expanded even further for good breeding to take place.

Commercial Black Ghost Knife breeders employ enormous breeding tanks to accommodate even the youngest of the species. Most aquarists cannot afford the large sums of money required to put up breeding apparatus.

Purchasing a decent batch of the Black Ghost Knife is the best option here, and given its long lifespan, there’s no need for an expensive and time-consuming breeding process.

How to Breed Black Ghost Knife Fish

In aquaculture, ghost knife fish (Apteronotus albifrons) barely reproduce. This is partly due to their size (big specimens can grow to be 20 inches long), but the species’ temperament also presents difficulties: Aggression toward related species kept in the same tank is common in ghost knife fish, making pairing difficult. Aquarium hobbyists can sometimes induce spawning activity and discover fry in the base of their aquariums.

Male or Female

The male and female black ghost knife fish have no such names. To detect a fish’s sex, people commonly look at its eyes. Male fish have eyes on the top of their heads, whereas female fish have eyes on the front. In addition, when compared to male blackfish, females produce higher velocity electric organ impulses.


Black ghost knife fish are more susceptible to skin disorders than other species due to their coloring. This is because that they lack the mottled skin protection that other fish have. Ich is always a sickness to be aware of, just as it is with other freshwater fish. This will manifest itself as white patches on their skin (which will be easier to recognize due to their dark hue), as well as a shift in their behavior.

If they are cut or scraped, there is a greater chance that they will become infected. It is critical to keep an eye on any cuts you notice to ensure they’re healing properly.


Are Black Ghost Knife Fish Blind?

The Black Ghost Knife fish is a South American tropical freshwater fish. These fish are reclusive, meaning that they are most productive at night and sleep throughout the day. Because they are most energetic and have poor eyesight, they forage and interact using an electromagnetic field.

Do Black Ghost Knife Fish produce electric shock?

Yes, because they have nearly little use of their sight, Black Ghost Knife fish have a tiny electrical sensor near their nose to detect and smell. The Black Ghost Knife fish is a predatory species that is always on the lookout for food at night. The sensor produces a modest electric current in the water that is undetectable by other fish and does not hurt them.

How do Black Ghost Knife Fish sleep?

The Black Ghost Knife fish is a South American tropical freshwater fish. These are nocturnal fish, meaning they are active at night and sleep during the day. They will emerge from their hiding location throughout the night after settling in to the new habitat and swim largely towards the base or leaves and plants.

Do Black Ghost Knife Fish have teeth?

No, just a beak-like mouth that is enlarged in some way. They are not known to bite, so you can serve them with your hands. When doing this, make sure your hands are completely clean because any external particles could cause illness.

Where can I find Black Ghost Knife Fish for sale?

You can shop your black ghost knife fish online at Aqua Imports online store. You can also shop physically at Aqua Imports, 2690 28th Street, Boulder, CO 80301.

The cost of black ghost knife fish varies between $14.99 and $149.99 depending on the size.