What Are Proper Black Ghost Knife Tank Mates?

Not every freshwater aquarium has to be a burst of vibrant color. You sometimes want something unusual as the centerpiece of your aquarium, and that’s when the black ghosts come in handy.

This species has a simple appearance, with the colors simplified to the main black with a bit of white on the tail. But it still features a strange charm, making it get a fair amount of attention from the aquarist community.

Like other aquatic inhabitants, the black ghosts must live with suitable tank mates to live and thrive. So what are proper black ghost knife tank mates?

Let’s find out!

Black Ghost Knife Tank Mates

Black Ghost Knife fish

The black ghost must live with suitable tank mates to live and thrive

Proper Tank Mates For The Black Ghost

Black ghost knife fish can be predators, so you will want to keep it with species of comparable size. We recommend considering species with peaceful temperaments.

Ensure that all aquatic inhabitants have the space they need. It might double if you keep a pair of black ghosts in residence. As long as no one gets their fins stepped on, it is possible to pair up any of these options:

  • Oscar
  • Bichir
  • Discus
  • Angelfish
  • Rope fish
  • Severum
  • Geophagus
  • Silver dollar.
  • Corydoras
  • Electric blue acara

Incompatible Species

First, you will want to avoid smaller fish. The reason is not necessarily because black ghost fish will turn into bullies. Instead, they will determine those little ones are snacks.

On the other hand, you do not want to keep a mixed fish tank. Snails and shrimp are part of a natural diet of black ghost knives.

A Guide On Black Ghost Knife Fish Care

care guide for black ghost fish

A care guide for black ghost fish

Water Parameters

The water parameter in the tank that this fish accepts will be quite flexible.

The reason is that its natural habitat is anything, as long as it is clean. But it is pretty sensitive to suboptimal water conditions.

Unlike other hardy species, it cannot tolerate average water quality. Here are our recommendations for water conditions for your black ghosts:

  • Water hardness: From 0 to 10 KH
  • pH levels: From 6.5 to 8
  • Water temperature: From 73°F to 80°F


Tank Size

The minimum aquarium size for a single black ghost fish is 100 gallons. This species will grow to be large and requires an aquarium that is big enough to accommodate it.

Increasing the tank size is needed if you plan to have many black ghost knives in your tank. Ideally, add 80 to 100 gallons per extra fish. It will minimize the chances of these fish showing aggressive behavior toward others.

Minimum tank size 100 gallons for one
Average lifespan From 10 to 15 years
Water temperature From 73 to 80°F (From 23 to 26°C)
School size No more than two; alone is okay
Adult size From 18 to 20 inches (or 45 to 51 cm)
Nitrite or ammonia 0 ppm
Nitrate <30 ppm
Hardness From 0 to 10 dH
Behavior Active and peaceful

Recommended Food & Diet

Black ghosts are strict carnivores

Black ghosts are strict carnivores

Black ghost fish is a strict carnivore. It has developed electrolocation to hunt in its river systems’ dismal waters, gathering signals from its prey. So you cannot convince this fish to switch to commercial fish food.

You should keep a healthy stock of live or frozen protein sources. Although they are not colorful, try to keep a variety on your hand.

Lucky, black ghost knives are not picky, allowing you to choose from any of their favorites. These including:

  • Krill
  • Crickets
  • Tubifex worms
  • Bloodworms
  • Brine shrimp.

Black ghost knives are nocturnal fish, meaning you must think about when you should feed them. We recommend feeding them in the evening (or even before going to bed).

In addition, you should avoid overfeeding them. If they cannot finish what you deliver in several minutes, just cut back.


How Long Is Black Ghost Lifespan?

The lifespan of these animals is approximately a decade under proper care conditions. But it can increase up to fifteen years in some cases!

Some main factors can influence their lifespan, including overall care quality and genetics. Do your best with any factor you can control, and they will last longer.

What Is the Appearance of the Black Ghosts?

This species’s name, “ghost knife,” is directly related to its appearance.

It is easy to see a distinct taper at its tail, made more apparent by the lack of dorsal fins. With only a few white rings around its tail, it is easy to pick out that slender “blade” shape. It explains the word “knife” in the species’ name.

So what about the word “ghost”? This word involves local mythology. Tribes in the area agree that when someone is gone, their soul will transfer into and inhabit the body of these unusual fish.

How to Distinguish Gender in Black Ghost Knife?

It is challenging to determine external differences between female and male black ghost fish. It is one of the hurdles in attempting to breed them successfully.

What Is the Size of the Black Ghost?

This species can reach 18 to 20 inches when fully mature.

What Is the Behavior and Temperament of the Black Ghost Knives?

Generally, black ghost knives are relatively active fish that love to do their own thing and be left alone. Although they have an aggressive side, it will only happen when they are around other black ghosts.

Do not worry! It does not mean you cannot keep two or more in your tank.

What To Include In black ghosts’ Tank?

Gravel or fine sand is best. Any typical rocks, driftwood, aquarium plants, or caves will work great as ideal hiding places.

The Bottom Line

Besides giving you suggestions about black ghosts’ tank mates, we have also brought you all the information you need for black ghost knives to live and thrive. Hopefully, this information will be helpful to you.

Thank you for reading!