Black Ghost Knife Fish Care: Size, Lifespan, Food, Tank Mates, Tank Size

Black Ghost Knife Fish is one of the most popular Knife fish species and an unusual gem that will be the centerpiece when kept in freshwater aquariums. This is not a new fish in the Aquarium industry.

For many years, fish keepers have picked the Black Ghost Knife Fish as an aquarium pet because of its stunning and unique appearance. If you have been searching for a gentle and beautiful fish, nothing will impress you like the Black Ghost Knife Fish.

From the way it is stunning black to its electrical sensory technique and nocturnal behavior, they are just irresistible. Its mesmerizing behavior and ease of becoming tamed rounds up the list of characteristics that make this fish species a perfect fit for any freshwater tank.

The story behind its name ‘Ghost Knife Fish’ is very interesting. It is actually told by the South American Tribes living in the Amazonian jungle. This name came to be from a common belief that the dead peoples’ souls in the region inhabited the fish.

Despite there being no sufficient evidence to support this belief, it is still something to make you keep this fish- you will have an interesting story to narrate about the fish to anyone who visits your home.

In this post, we will discuss all the important details about the Black Ghost Knife Fish and explore all its care requirements. Follow through to learn whether it is worth a spot in your display Aquarium or not.

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Quick Facts:
Common Names	: Black Ghost Knife Fish, Black Ghost Knifefish, Apteronotid Eel, Black Knife
Scientific Name	: Apteronotus albifrons
Family	: Apteronotidae
Origin	: Tropical freshwater bodies of South America
Care Level	: Moderate
Lifespan	: Upto 15 years
Size (average)	: Upto 20 inches
Diet	: Carnivores
Breeding	: Egglayer
Social	: Community fish
Temperament	: Semi-aggressive
Minimum Tank Size	: 100 gallons
Temperature	: 73 – 82 °F (22 – 28 °C)
Water Hardness	: 5 - 19 dGH
Water pH Level	: 6 - 8

Table of Contents

Overview of Black Ghost Knife Fish

These species are scientifically named Apteronotus albifrons while are alternatively called Apteronotid Eel and Black Knife. The Black Ghost Knifefish is a medium-sized, long-bodied, scaleless fish.

It belongs to the Apteronotidae family and the speckled group of knife fish.

It is one of the most peaceful species among the Knifefish family and the best to keep in a community tank. When well cared for the Black Ghost Knifefish will grow up to 20 inches long.

The Black Ghost Knifefish boasts a stunning black theme and white marking beautifully placed on the tail and nose regions. This, in addition to its ‘knife’-like body shape, makes the Black Ghost Knifefish look very charming as it slowly swims along contrasting fish mates.

The Black Ghost Knifefish is carnivorous and will enjoy feeding on chopped meat, earthworms, and all sorts of frozen and flaked foods.

The eyesight of the Black Ghost Knifefish is poor, but thanks to its ability to generate low voltage electricity via an organ in its tail, it can still navigate through murky waters, where it enjoys living.

This feature also allows the fish to communicate and detect food in the habitat. The other peaking feature of the Black Ghost Knifefish is its extended lifespan of 10 to 15 years which most tank fish will struggle to clock.

If well taken off, this is the kind of fish that will glam up your Aquarium and be your companion for as long as your tank exists.

The last most interesting feature of the Black Ghost Knifefish is its nocturnal behavior. Unlike most fish, the Black Ghost Knifefish will be highly active and thrilling during the night.

They spend most of their daytime hiding and relaxing. The fish prefers its own company but will also live peacefully with other non-aggressive and calm fish.

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Black Ghost Knife Fish Size

This fish is exceptional in all aspects and when it comes to size. A Full Grown Black Ghost Knife Fish size is up to 20 inches in length. Although the fish does not broaden significantly, its slim and elongated body is absolutely breathtaking.

If you are a fan of medium to large aquarium fish, this fish will, without a doubt, win your heart. This fish is fast-growing and if fed properly, they will reach maturity and Black Ghost Knife Fish full size faster.

Keep in mind that the quality of the breed you buy will dictate how fast or how big your Black Ghost Knife Fish size will grow. In this regard, only use reliable breeders offering premium stocks for the fish.

Black Ghost Knife Fish Lifespan

As mentioned above the Black Ghost Knifefish has quite a long lifespan. When if it is optimally cared for, it can live up to 15 years. This is a decent period considering that with its scaleless body, people expect it to be one of the short-living tank fish.

Black Ghost Knifefish Colors and Special Markings

Let’s dive into the most important characteristics that enable us to know more about this unique fish species.

The fact that the fish is not all colored and marked is one of the most striking features of the Black Ghost Knifefish. Even if the fish is not the brightest in a community aquarium of other fish species, it will still stand out as unique.

Their nocturnal behavior also means that they will thrill at night when most of the other tank fish are in their hideouts and when lighting clearly brings out their unique black theme.

As the name Black Ghost Knifefish suggests, this fish’s body assumes the shape of a knife. The shape is achieved by lack of caudal and dorsal fins on their body.

What can be said to their primary finnage system is a long continuous fin that runs on its underside along the entire body length. The finnage swings sideways to facilitate the attention-capturing swimming of the Black Ghost Knifefish.

Again, their body is flat and elongated, a feature that brings out clearly, the ‘knife’ shape as they swim. The other distinctive feature of the Black Ghost Knifefish is that it does not have scales and its body is covered by skin entirely.

It is needless to say that this comes with its own set of negative implications, one of them being high susceptibility to diseases.

As mentioned above, the Black Ghost Knifefish can emit and receive an electric signal and this is enabled by an organ found in the tail. The weak electric organ is very crucial as it also helps it to locate food.

As mentioned above, there is not much to talk about its colors and markings. The fish is generally matte black with two white markings strategically placed on its body.

Due to breeding and environmental adaptations, the fish may also appear in shades of black. One white mark is on its tail, while the other is found on the nose area and sometimes extends to the back region.

Black Ghost Knifefish Care

If the Black Ghost Knifefish had scales, it could be one of the easiest tank fish to care for. Most of the care actions that the fish requires will be aimed at ensuring that its sensitive skin does not contract diseases.

It is needless to say that one of the easiest ways to keep this fish healthy in its scaleless condition is by maintaining very stable tank conditions. Let’s explore some specific tank parameters and aquarium care and conditions for this fish.

– Tank Conditions and Care

First, the tank should be sufficiently large to accommodate this massive fish. You need to add some crucial components to the Black Ghost Knifefish’s tank to improve their living experience.

The first and most important component is a filtration system. It will keep the tank water at the required quality at all times.

It would also help if you included a UV sterilizer to help kill any bacteria that may harm your fish by bringing infections to your Black Ghost Knifefish.

You also need to partially replace the water every week (30-50%) to supplement the work that your filtration and sterilization system of keeping the water quality in check.

The substrate, lighting, and planting should emulate as much as possible what their wild environments offer. Let’s briefly discuss each of these tank parameters.

– Black Ghost Knife Fish Tank Size

The minimum Black Ghost Knife Fish tank size should be at least 100 gallons tank because it is a long-bodied fish that is up to 20 inches long. To accommodate 2 to 3 Black Ghost Knifefish species, the minimum Black Ghost Knife Fish tank size you must have is 150 gallons aquarium.

For a community fish tank, the size will depend on other members’ requirements in the tank, but it definitely needs to be more than twice or thrice this size.

– Black Ghost Knife Fish Tank Setup

Since the fish is used to living in dark conditions, it would be best to provide medium brightness subdued lighting. Before you set up this kind of lighting, factors in what other fish in your community tank require.

For the substrate, replicate what their natural habitat offers by adding a mixture of aquarium sand and gravel to the tank’s bottom.

Tank decorations such as wood logs and aquarium rocks will give your Black Ghost Knife Fish perfect hiding and relaxing spots. Keep them on the sides in order to leave enough room for the fish to roam in the aquarium.

– Suitable Plants

Aquarium plants included in a Black Ghost Knife Fish aquarium are exclusively for the purpose of increasing their hiding places. Remember, these fish are carnivorous and will not eat the tank plants you include.

In this regard, you have the freedom to include as many live aquarium plants as you wish. This fish will do well with absolutely any water plant but preferably those with high foliage like the Water Wisteria.

– Water Condition and Parameters

The fish will enjoy medium to strong flowing water, so consider this when you choose the aquarium filter for your Black Ghost Knifefish tank setup. It is also recommended to test the water on a weekly basis to ensure that the nitrate and ammonia content is at the required level.

For the water conditions, maintain them as follows:

Water temperature: 73 – 82 °F (22 – 28 degrees Celsius)
Hardness: 5 – 19 dGH
Acidity: 6.0 – 8.0

The secret here is to maintain these parameters in a stable condition at all times. Make sure you keep continues water testing with the Aquarium water testing KIT to avoid any water conditioning issues.

Black Ghost Knifefish Diet and Feeding

The Black Ghost Knifefish is carnivorous and will snack on a wide variety of carnivorous meaty food. Their favorites are bloodworms, brine shrimp, blackworms, and mosquito larvae.

This fish will eat during the day and at night when it is most active. It is recommended to feed the Black Ghost Knife Fish several times a day with just enough food.

If your tank lighting is subdued, it is more practical to feed your Black Ghost Knifefish at night.

Black Ghost Knifefish Typical Behavior

The Black Ghost Knife Fish is a shy, peaceful fish that will live harmoniously if kept with its own company. Keeping them with other Knifefish can trigger their aggressiveness, the last thing you would want from a peaceful fish.

If they are stressed or feel threatened, they may exhibit aggressive behaviors, especially to similar or smaller-sized tank mates.

The most distinguishing behavioral characteristic is that it is nocturnal. The fish is very active at night and will spend most of the day time hiding and resting.

This is not mean that they will totally be absent during the day. They will still come out to swim during the daytime when they are excited and feel like displaying their uniqueness.

Since they don’t have well-developed eyesight, they interestingly communicate with the help of an electric field (follow through to know how this happens).

On settling in a comfortable environment, these fish will spend most of their free time at the bottom of the Aquarium. They only come out from their hiding places at night unless they feel comfortable in the environment.

Even at night, they will only swim near the substrate and the foliage. The right terms to describe the Black Ghost Knifefish are gentle and reserved.

Common Diseases

Although the Black Ghost Knife Fish is generally a hardy tank fish, its scaleless body exposes it to the risk of getting certain diseases, the most common one being ich.

The symptoms for ich are white spots on the body and changes in normal behavior. The good thing with ich is that it is treatable with over-the-counter drugs.

For this condition, it is advisable to treat the whole population as, in most cases, the entire community will be infected. These fish are also prone to skin infections, including flukes, bacteria, and protozoa infections.

Gender Differences

There are no major differences between the male and female species of this fish. The only sexual dimorphism is the electric fields they generate and emit.

Research findings show that the female Black Ghost Knife will generate and emit more electric fields than the male species.

Due to this, the females may show more response to food and companions than the males, but even with this, it is still hard to distinguish them.

Black Ghost Knife Fish Breeding

Breeding the Black Ghost Knife is almost impractical in a home aquarium. The main reason behind this is the large tank size requirement that will even require to be increased for successful breeding to occur.

Commercial Black Ghost Knife breeders use extremely large breeding tanks so that they can handle even the young ones. The huge capital required to set up the breeding equipment is not affordable for most aquarists.

What’s more, the exact procedures followed to breed these fish are only known to commercial breeders. Doing it your own way may either be unsuccessful or confusing along the way.

Buying a good batch of the Black GhostKnife is the real solution here and considering its impressive lifespan, there is no need for an expensive and highly demanding breeding process.

Black Ghost Knife Fish Tank Mates

When you choose Black Ghost Knife Fish tank mates, you should consider the temperament of the fish species that you are planning to keep with them. Even they grow up to 20 inches they are very peaceful. So you should keep with peacefully tank mates.

The perfect Black Ghost Knife Fish tank mates include:

The Corydoras is an excellent tank mate as they will, in addition to being great companions to your Black Ghost Knifefish, help keep the tank clean.

Origin, Distribution, and Availability

The Black Ghost Knifefish is native to the tropical freshwaters of South America. In this region, the fish is highly populated in the stretch between Venezuela and the Paraguay Parana River.

The Amazon basin is also populated with this elegant and beautiful fish species.

In the wild, the fish prefers to live in highly vegetated areas. The places where there are lots of hiding places. Most of the time, the Black Ghost Knifefish will be found in slow-flowing water bodies, preferably those with a sandy bottom.

The lighting here is low, a condition that needs to be simulated in aquarium environments. During the wet season, the Black Ghost Knifefish migrates into the flooded forest.

Just like any other popular aquarium fish, the Black Ghost Knifefish did not struggle to get to other parts of the world. The fish first spread to other parts of America before it was transported to far distant regions.

This is because breeding was done to tone the fish to specific climatic conditions. Today, you can find the Black Ghost Knifefish in physical or online pet shops.

The price of one Black Ghost Knifefish averages around $20 to $50 in the US market.

Frequently Asked Questions

The general questions that we think of are discussed below. Got more questions that came to your mind when you are reading the guide? Please include them in the comment section at the end of this article.

Is It Possible For The Black Ghost Knife Fish To Live With Other Fish?

Yes, but they have to be non-aggressive and preferably the same size or slightly bigger or smaller. Very tiny fish will be apprehended as food and should not be kept in a Black Ghost Knifefish tank.

Do Black Ghost Knife Fish Grow Fast?

The Black Ghost Knifefish is a fast-growing fish species. When correctly fed and generally taken good care of, they will reach maturity within two years.

Keep in mind that they can grow up to 20 inches long, meaning that this is a very impressive growth rate. Growing fast also means that they will stay most of their life in the same body size.

Are Black Ghost Knifefish Fin Nippers?

The Black Ghost Knifefish is naturally not a fin nipper. However, if pushed to be aggressive, they can pursue their threats with their tail.

Is The Black Ghost Knife Fish Aggressive?

The Black Ghost Knifefish is generally peaceful and will rarely cause any form of trouble or chaos in your aquarium. With the right tank size, water conditions, and tank mates, you will barely see their aggressive side.

Do Black Ghost Knife Fish Have Teeth?

No, just a beak-like and somehow elongated mouth. You can even feed them from your hands as they are not known to bite. Please ensure that your hands are very clean when doing this as any foreign elements may lead to infections.

Final Thoughts

The Black Ghost Knifefish is a must-have for both beginner and seasoned tank fish keepers. Its unique black theme is something that will shift the focus of your eyes. Because we used to just see vibrantly colored fish in a freshwater display aquarium.

The distinctive features of this fish will be seen when kept with colored compatible tank mates. Even if this fish species is termed as semi-aggressive, it is one of the peaceful fish when kept under the right spacing and tank mate’s conditions.

Many fish keepers who share their experiences about this fish say that they hardly see its aggressive side. Yes, other Knifefish species can be aggressive predators. But, the Black Ghost Knifefish is an exception therefore it is a common addition to aquariums.

The fish is fast-growing, not to mention that it has an exceptional lifespan. This is what a tank fish keeper would be looking for from a tank fish. It would be unfair not to acquire this gentle, beautiful, fun, and easy-to-care-for fish for your aquarium after reading this.

Head out to your local pet store, get this gem and have the real experience interacting with the Black Ghost Knife Fish. We assure you that you will be happy when you get a Black Ghost Knifefish for your tank, so go for it now!

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