Can angelfish live with black ghost knives?

Verdict

No. Angelfish and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 6 inches angelfish do.

Angelfish76–84°F · pH 6–7.5

Black ghost knife73–82°F · pH 6–8

What to watch

Deal breakerAn adult black ghost knife eats fish that fit in its mouth, and at 6 inches angelfish do.
Watch outBlack ghost knives are much bigger and pushier than angelfish, which are slow and easy to bully at feeding time.
Watch outBlack ghost knives grow to 15 inches and need 125 gallons, far more than a tank set up for angelfish.

What works

Both are fine at 76–82°F.
pH 6–7.5 suits both.
They use different parts of the tank: angelfish the mid, black ghost knives the bottom.

Water side by side

The green band is the temperature range both can live in.

The green band is the pH both tolerate.

Size to scale

Adult length in an aquarium. A fish can swallow anything that fits in its mouth, roughly a third to half its own length for predators.

Care at a glance

	Angelfish	Black ghost knife
Temperature	76–84 °F	73–82 °F
pH	6–7.5	6–8
Adult size	6.0 in	15.0 in
Minimum tank	30 gal	125 gal
Temperament	Semi-aggressive	Semi-aggressive
Swims at	Middle	Bottom
Group	Alone or in pairs	One per tank
Diet	Omnivore	Carnivore

Better tank mates for angelfish

All angelfish tank mates

Better tank mates for black ghost knives

All black ghost knife tank mates

Questions

Can angelfish live with black ghost knives?

No. Angelfish and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 6 inches angelfish do.

What temperature suits both angelfish and black ghost knives?

76–82 °F. Angelfish need 76–84 °F, black ghost knives need 73–82 °F.

What size tank do angelfish and black ghost knives need together?

At least 125 gal, set by the black ghost knife. Add space for each extra fish.