Black Ghost Knife Fish Tank Mates – What Are The Best Choices?

The black ghost knife fish are arguably among the most peculiar freshwater species that you have laid your eyes on. With their unique appearances, black ghost knife fish remains pretty much a mystery to inexperienced aquarists.

Hence, not much is known about black ghost knife fish tank mates, their lifespan, and how to take care of them correctly. In case you are curious about these animals, let’s keep reading and find out for yourself!

Black Ghost Knife Fish Tank Mates

Black ghost knife fish are not known to be aggressive. Despite their large size, these fish enjoy being left alone. Therefore, lots of peaceful, easy-going fish can share the same living territory as black ghost knife fish.

Dojo Loach

Dojo Loach

Dojo Loach stands out with their vibrant color skin, which can act as decor for your tank. Furthermore, this type of fish is friendly and active, just like black ghost knife fish.

The only problem you have to be mindful of is to find an aquarium big enough for both of them since Dojo Loach can grow up to 12 inches!

Rainbow Cichlid

Rainbow Cichlid

Rainbow cichlids are hardy and highly accessible, making them a treat for amateur aquarists. Moreover, they are small enough that having a few of them will not become a threat to your black ghost knife fish.

If you want to add a few brighter shades to your tank, these animals will not let you down.

Cory catfish

group of cory catfish

Cory catfish have an average length of no more than 2.5 inches. But their tiny size does not prevent them from looking visually pleasing when placed inside your tank.

As far as temperament is concerned, cory catfish mostly spend their time swimming around. They do not engage in fights and are not intimidated easily by black ghost knife fish’s looks.

Electric Blue Acara

Electric Blue Acara Cichlid Fish

If you are into brightly-colored fish, the Electric Blue Acara is a perfect choice. Not only does it have shiny blue skin that compliments the black ghost knife fish’s appearance, but it is also easy to live with.

The fish itself is known for their quietness, so you can expect it to be rather still and harmless.

Black phantom tetras

Black phantom tetras

Given how small and peaceful tetras are, all strands of this species can very well fit inside your tank. However, if you want something a bit less common, consider going for the black phantom tetras.

With their iridescent scales, black phantom tetras provide a touch of illumination for your aquarium.

Black Ghost Knife Fish – What You Need To Know


Most people agree that black ghost knife fish can live up to 10 years in captivity. That being said, if the conditions are optimal, expect these animals to live up to 15 years!

All you have to do is to be mindful of their water quality, surrounding environments, and diet.


A black ghost knife fish looks nothing like a usual fish. Instead of having a caudal or dorsal fin, black ghost knife fish pride themselves on having merely a thin ridge.

The entire length of their body is curved like a knife, hence the name. Furthermore, the closer you get to their tails, the more elongated the fish appear to be.

As for the color, the black ghost knife fish is covered entirely in black, with the exception of several white stripes and spots.


Black ghost knife fish do not enjoy having pellet foods or flakes. As a result, most aquarists have to switch to live or frozen food. Anything rich in protein that resembles the natural diet of black ghost knife fish is highly recommended.

If you are not sure about what to feed your fish, just go for the regular options. Tubifex, bloodworms, brine shrimp, and brine shrimp eggs will suffice.

Tank setup

As black ghost knife fish are no small animals, you have to invest in a 100-gallon tank. This tank size provides your fish with enough space to move around comfortably and leaves some more room for smaller tank mates.

Black ghost knife fish are not picky when it comes to water parameters, but it does not mean you should settle for less. An ideal range of temperature should be between 73 and 80 degrees Fahrenheit, while the pH levels should not fall under 6.5 or exceed 8.

Now, what black ghost knife fish particularly care about is the water conditions. If they are not clean enough, you surely will see signs of protests coming from your fish.

To prevent them from getting stressed or developing serious ailments, consider buying a water test kit. This small yet powerful tool will give you a quick look into your water’s quality.


1. Do black ghost knife fish need an air pump?

Yes. Given how large black ghost knife fish is, it will be an inconvenience if your tank lacks a constant source of oxygen. Having an air pump ensures a steady flow of oxygen inside the water, thus securing the livelihood of your fish.

2. How fast do black ghost knife fish grow?

Within the first five years, the growing speed of black ghost knife fish is something to be careful of. Each year, they will become 4 – 5 inches longer than the last, culminating at no fewer than 20 inches when reaching adulthood.

3. Do black ghost knife fish give an electric shock?

No. It is true that black ghost knife fish does produce an electric current through their spinal cord neurons. However, the generated electricity is not powerful enough to stun, shock, or kill anyone.


Now that you have learned about black ghost knife fish tank mates, make sure to create an ideal community tank for them! As long as you pair black ghost knife fish with the right companions, these animals will surely have a good time.