Black Ghost Knife Fish

Black Ghost Knife Fish Care Guide


There seems to be an endless list of interesting facts about the black ghost knifefish, and we have another one to add to the list .They do not have scales or fins contrary to other fish. Almost like a flying fish or a sting ray, the black ghost knifefish has billowing sides that makes it look like it glides through water. It doesn’t have a caudal or a dorsal fin either and greatly resembles a knife.

Because it doesn’t have scales, the black ghost knifefish is extra tough to care for because they are more susceptible to changes in water parameters and common fish diseases. The source of their electric reception and emission is located on their tails. It’s difficult to sex the black ghost knifefish, but studies have shown that the females have a higher electrical frequency than the males. Further studies have been made to learn more about their development.


How big does a black ghost knife fish get? When they are completely stretched out, the black ghost knifefish can reach up to 20 inches long!


As you can imagine, the black ghost knifefish is a solid black color with only a few white decorations. The white spots are seen on their tails and their noses.


If water conditions are maintained to a tee, your black ghost knifefish can live in the aquarium anywhere from 10-15 years!


The black ghost knifefish is fierce-looking species that lives on a carnivorous diet. They get a steady supply of insects, larvae, smaller fish and worms in the wild. You should try to simulate this diet as much as possible in captivity. This means you would need regular feedings with bloodworms, brine shrimp and other fresh or frozen foods.

They are not picky eaters, but it could take them a while to get accustomed to fish flakes and pellets. Even when they have become accustomed to this diet, we would still suggest balancing it with regular supplements of live and frozen food. In order to know the exact amount to feed your black ghost knifefish, observe them when feeding. They shouldn’t need more than the amount they can consume within 5 min.

Be sure to feed the black ghost knifefish at night as well, since that is when they would naturally feed. Being nocturnal, you may have to get used to caring for your black ghost knifefish differently. In the beginning when they are first brought home, it will be more difficult to gauge how much to feed them because it will take them a while to come out of hiding and graze.

However, when they finally make the attempt, give them some time and make sure you clear the leftovers from the tank as soon as possible to maintain the integrity of the water. Black ghost knifefish are quite docile when it comes to their owners, and other than being very “pettable”, some aquarists have even trained their fish to feed from their hands. It could take some time and a lot of patience, but this is another option if you experience difficulty getting them to eat.


The black ghost knifefish is from the apteronotidae family and is a tropical freshwater fish native to South America.

Tank Conditions

The black knife ghostfish can be found all over South America, in the warmer waters of Venezuela all the way to freshwater basins in Peru. If you take a look at the rivers and streams in these areas, you will see that they are full of plants, rocks and places for the fish to dart in and out of.

It’s best to keep the aquarium conditions like so with murkier waters and not a lot of sunlight. In these areas, the water flow is also apparent, but not too aggressive. Since they have a more timid nature and their natural environment is full of these places, make sure you give your black ghost knifefish plenty of places to hide.

Look into plenty of rocks and vegetation. Natural plants are best but if you decide to place artificial ones, make sure that there are no sharp edges in case they injure your black ghost knifefish. The scaleless attribute is a unique one, and requires more consideration when decorating the tank.


They are more accustomed to warm waters, so the temperature for the aquarium should be at 73-82 degrees Fahrenheit (23-28 degrees Celsius).

Water Conditions

As for the water conditions, the pH level should be relatively neutral at 6-8 and water hardness of 5-19 dGH.

Minimum Tank Size

They can grow to be quite large in size, and the minimum tank size for a single black ghost knifefish is 100 gallons. As mentioned, they are quite friendly towards other fish in an enclosed space, unless they are other knifefish or ones that resemble them. If placed with another black ghost knifefish, make sure you have a large aquarium adding 80-100 gallons per extra fish.

Maintenance and Care

You need to have adequate experience to handle a black ghost fish. They are extra sensitive due to their anatomy, so investing in instruments such as a water filter and UV sterilizer can make your job easier. As you can imagine, the lack of scales make the ghost fish particularly susceptible to skin diseases such as Ich (which is very common).

You know they are having skin issues when they start to rub themselves on surfaces around the tank. This signifies that they are itching. Their monochrome color also makes it easy to spot skin abnormalities, so keep a close watch on them.

Luckily, most skin diseases are quite easy to treat, but make sure they are never given copper-based medicine because they cannot handle it.

Suitable Tank Mates

When you introduce a black ghost knife fish to the tank, you need to know if it was bred in captivity or captured in the wild. This is because if its from the wild, you may need to isolate it in its own take for a while before introducing it to the community aquarium because they can transfer foreign bacteria into the tank and perhaps soil the condition of the aquarium.

The black ghost knife fish is generally considered to be a peaceful fish unless they see other similar fish or other knifefish. When thinking about introducing tank mates, try to opt for ones that are similar in size (not appearance) and temperament as well. Cichlids can have some aggressive breeds (firemouth, green terror), but peaceful ones can make great companions.

Catfish and tetras are good with the black ghost knife fish as well, but make sure the aquarium mates you add are not small enough to be mistaken for food. Another instance where they can be aggressive is if the tank is too small, so make sure you have a tank large enough for all the species you plan to keep. A good rule of thumb is to opt for species around 10 inches (a little less is fine) and have a good disposition.


As another general rule of thumb, do not keep black ghost knifefish with its kind or other similar species if you do not have a large enough tank. We also suggest keeping the maximum at 2 black ghost knifefish and no more than that. If you give them enough space to swim there will less likely be fights that break out. Larger peaceful fish are the optimal choice.


They are very large, which makes it hard to breed these fish in captivity. Your aquarium will need to be very large to house both a male and a female, and in cases where there have been successful cases of breeding, the methods have been debated. They are mainly bred in commercial facilities (a large one in Indonesia), but little information is known about the process.

A pond is the better alternative to a large aquarium and can actually simulate the right environment much more easily. If you decide to attempt this difficult breeding, there are some conditions you must adhere to. We would also strongly advise approaching breeding with a level of caution, since there is a limited amount of information out there and rarely any successful cases in captivity.

You need a male and female black ghost fish, which presents the most difficulty. They need to be a bonded pair that can be attempted by you but it mostly happens naturally. Then the aquarium or pond comes into question. You need it to be large enough for both, so we are looking at AT LEAST 180 gallons.

This aquarium or pond would need to be in a dimly lit area without direct exposure to sunlight. It should be near a noisy area or one with a lot of foot traffic or movement. As for what goes into the tank, you need to be prepared to populate it with plenty of vegetation and rocks and other surfaces for them to hide. Much like some other species, these fish are prone to consuming their eggs for food after spawning.

We think you may be interested in: Best Pond Liner

The female won’t spawn if she is stressed or feels as if she might be in danger, this is another reason why it’s so imperative to have enough hiding places in the tank.

You need to have a secure place to place the eggs or remove them. Keeping the water temperature a bit warmer, around 27-28 degrees Celsius is also recommended. The parents will also need flooding and draining consistently. This changing of the aquarium will serve to signify the wet season in South America and will hopefully trigger breeding.

Pond breeding has more of a chance of success compared to aquarium breeding. One thing is for sure, you must always keep the conditions at optimal levels as these fish are extra sensitive.

Let’s say you are successful in breeding, then you should actively remove either the eggs or the parents (the parents being the easier choice). You should see the fry in about 3 days and start with a steady diet consisting of infusoria, then some sort of meat-based meal such as brine shrimp, they move on the flakes. When they are old enough, about a month or two, you can introduce them to a more varied diet.


Due to their eye-catching and unique appearance, the black ghost knifefish is an immensely popular fish in the aquarium trade. However, their beauty isn’t without a price as it also takes extra effort to care for these fish. Their temperament is one thing that doesn’t cause any problems because they are very friendly – until they meet their own kind.

Other black ghost knifefish and similar-looking species can set them off, especially if your tank isn’t large enough. Due to them being a scaleless fish, you also need to be extra careful as to what you place in the tank. This lack of protection is precisely what makes them extra sensitive to diseases. On the bright side, the black ghost knifefish is single-colored and this makes it easy to spot potential issues.

Other unique traits of this fish are their electrosensory organ and being nocturnal. They have poor vision and rely on the emission and reception of these electric signals to map out their surroundings and communicate. As an aquarist and keeper of the black ghost knifefish, you need to make sure you do all your feeding (a carnivorous diet) and other interactions at night.

They are quite the amazing additions to your tank and are a trainable fish as well. With enough patience and time, it’s more than possible to be able to pet these fish and have them eat out of your palm.

Source link

Leave a Reply