Care Guide for Black Ghost Knifefish – 18-Inch Electrical Oddball Fish

We receive a lot of inquiries for this care guide, as knifefish are so unusual-looking curiosities. Their undulating fin allows them both to swim forward and reverse. Although there are many types, the black ghost knives (BGK), which is easily available in the pet trade, is often the most popular and the most sought after. The black ghost knife (BGK) is a much larger pet than your average betta fish. They require a lot of space and can live more than a decade. Let’s discuss what it takes for this oddball fish to be happy and healthy long-term before you commit.

What are Black Ghost Knifefish and how do they work?

Apteronotus Albarons, a South American nocturnal fish, has poor eyesight and uses electrical signals to navigate. It lacks a dorsal nor caudal fin which gives it its common name, the “knifefish”. Instead, the knifefish has an extended anal tail that runs along its bottom and ripples in waves like a wave. It can maneuver bidirectionally within tight spaces thanks to this fin.

Black ghost knifefish are often kept in captivity and can cost anywhere from $15-20 depending on their size. A lot of juveniles are sold in small tanks. This can lead to them getting into fights with other fish. Be sure to choose a healthy one that has both the white spots and tail. You can expect this fish to live for as long as a pet dog. Ask the employee at the store to feed your new knifefish before you bring it home.

You want a healthy, active, and well-fed knifefish.

What size can a black ghost knife grow to? It is possible for them to get quite large if they are fed enough. Don’t be surprised when your baby knifefish grows into a 14-to-18-inch (35-45cm) monster.

How fast can black ghost knife fish grow. We have seen them grow up to 20 cm (20 inches) the first year. Then, the growth rate slows to around 2 inches (5 cm) each year.

Is the black ghost knifefish hardy? Many people call them “sensitive” fish that don’t live very long, but that hasn’t been our experience. Our success is due to their excellent nutrition, keeping them safe, and making sure they aren’t picked on. Fish can usually handle one stress factor but health problems are more likely if there are multiple stress factors.

Will a ghost knifefish shock you? This is because it is weakly electric, unlike a stronger electric fish like an electric eel. The knifefish’s electric organ creates a weakly charged electrical field. Other sensing organs can pick up slight distortions to the field. This detection system helps the knifefish to navigate its surroundings, locate prey, and communicate with potential mates or intruders.

How to Set Up an Aquarium for a Black Ghost Knife

Let’s talk about tank size. A 55-gallon aquarium might be okay for the first year, but it is too small for the long term. A 75-gallon fish aquarium is the next upgrade and may last for several more years. Ultimately, we recommend getting a 120- or 180-gallon aquarium for an adult black knife fish. They can tolerate a pH between 6.8-7.8, temperatures between 75-82degF (24–28degC), and minimum 5deg (90ppm). Create a heavily decorated setup with low lighting and lots of nooks and crannies – such as clear PVC pipes, rock caves, pleco caves, large driftwood, and aquarium plants. As they get larger, you can upgrade the size of the caves and tunnels to ensure they feel secure and surrounded.

Plecos might argue with your knife fish about the best hides. Provide more caves, if necessary.

Is the black ghost knifefish aggressive? In the right conditions, they can live in a community aquarium with other similar-sized, peaceful fish. It is not a good idea for tank mates to bully or outcompete you for food. You should also know that your adult knifefish will happily consume neon tetras as well any other small fish. Avoid any nano fish if it grows larger.

What fish can live with a black ghost knife? Hobbyists have kept adult BGKs with Geophagus “eartheater” cichlids, peaceful catfish, angelfish, and other friendly tank mates larger than 6 inches (15 cm).

Two black ghost knifefish can live together? This is a common problem. Knifefish are territorial and don’t like sharing their space with other electric fish, such as baby whale fish, elephant nose fish, and other knifefish. Obviously, anything is doable if you have a large enough aquarium, but most people tend to keep ghost knifefish in undersized tanks.

What do Black Ghost Knife Fish Eat?

They are relatively easy to handle and eat a primarily meat-based diet. They are able to eat both sinking and floating fish, despite being bottom dwellers. Ours like worms. Once they are old enough they will predate small fish and invertebrates.

Black ghost knives can be shy at first. They will want to stay in their favourite hiding place all day until it’s time for them to eat. Many people have taught their ghost knives to eat by using floating foods or out of their hands.

Black ghost knives are able to be trained to swim to the surface and eat directly from your hand.

Can black ghost knife fish eat flaked food? Flaked food is not nutritionally dense enough to sustain them long-term, particularly since they are easily outcompeted by other fish for food. We prefer to feed our fish pellets, freeze-dried, or frozen food to maintain their healthy weight.

This is a great species to have as a showpiece fish. The black ghost knifefish is a great pet if you’ve done your research thoroughly and are ready to buy a large tank. Although we don’t ship fish, please check our preferred online retailers for information about what they have.