Care Guide for Black Ghost Knifefish – 18-Inch Electrical Oddball Fish
This guide has been requested a lot because knifefish, which are unique-looking curiosities, have an undulating tail that allows them both to swim forward and reverse. The black ghost knife (BGK), although there are many varieties of knifefish, is the most commonly available and attracts beginners. This pet is much larger than the average betta fish, and requires more space. It can also live over a decade. Let’s first discuss how to keep this unusual fish happy and healthy over the long term.
What is a Black Ghost Knifefish, you ask?
Apteronotus albifrons is a South American nocturnal fish that has weak eyesight and instead uses electrical signals to navigate its surroundings. The common name “knifefish” comes from the fact that it has no dorsal or caudal fin, giving it a blade-like appearance. An extended anal fin runs along its bottom edge and ripples backwards like a wave. This allows the knifefish to maneuver in bidirectional fashion between tight spaces.
Black ghost knifefish are often kept in captivity and can cost anywhere from $15-20 depending on their size. Sometimes, young fish are sold in overcrowded tanks. They may get into problems with other fish. So make sure to buy a healthy one with both the white spots and a tail. Given that this fish can live as long as a pet dog, consider asking the store employee to feed them first so you can confirm your new knifefish is eating well before taking it home.
You want a healthy, active, and well-fed knifefish.
How big can a black-ghost knife get? If they get enough food, they can grow quite large. Don’t be surprised to see your baby knifefish grow into a massive 14- to 18-inch (35 to 45 cm) fish.
How fast does black ghost knife fish grow in their care? After the first year, they reach a height of 8 inches (20cm) and then slow down to 2 inches (5cm) per year.
Are black ghost knifefish tough? Some people think they are “sensitive” fish that can’t live long. However, we have not had that experience. The keys to our success include feeding them really well, making sure they don’t get picked on, and maintaining good water quality, as you would with any other fish. Although fish can normally handle one stress factor, multiple stress factors can increase the risk of health problems.
Will a ghost knifefish shock you? This is because it is weakly electric, unlike a stronger electric fish like an electric eel. A knifefish’s electric organ generates a weak electricity field. It also has other sensing organs which can detect slight distortions in this field. These organs are similar to radar systems. This detection system allows the knifefish navigate its environment, find prey, and communicates with potential mates or other intruders.
How to Set Up an Aquarium for a Black Ghost Knife
Let’s discuss 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, temperature between 75 and 28degC (24-28degC), as well as GH levels of at least 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. You can increase the size and comfort of your shelters for them as they get larger.
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 them for food. Neon tetras are a favorite food of adult knifefish, as well as any small fish, so keep any nano fish away from your tank.
What kind of fish can live with a ghost knife? Some hobbyists keep adult BGKs alongside peaceful catfish, geophagus cichlids and other friendly tank mates.
Can 2 black ghost knifefish live together? We don’t recommend it since problems tend to arise. 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 are the Black Ghost Knife Fish’s Favorite Foods?
They are very easy to keep and they eat a mostly carnivorous diet. They are a bottom dweller but will eat both floating and sinking fish food. Ours enjoy a variety of worms, bloodworms, brine shrimp, pellets that fit in their mouths, and freeze-dried foods. Once they are old enough, they will predate upon small fish and other invertebrates.
Black ghost knives may be shy at first, and will spend the day hiding in their favorite spot until they are ready to eat. Therefore, many people have trained theirs to eat out of their hands or from the water surface by using floating foods.
Black ghost knives are able to be trained to swim to the surface and eat directly from your hand.
Do black ghost knife fish eat flakes? Flake food may not be nutritionally dense enough for knifefish in the long run, especially since it is easy for them to get outcompeted for food by other fish. We prefer to feed our fish pellets, freeze-dried, or frozen food to maintain a healthy weight.
This is a great species to have as a showpiece fish. If you do your research well and are looking for a big tank to house it, the black ghost knivesfish might be the perfect pet. We do not ship fish. However, you can check out our recommended online retailers to see what stock they have.