Can pearl gouramis live with black ghost knives?

Verdict

No. Pearl gouramis and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 5 inches pearl gouramis do.

Pearl gourami77–82°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 5 inches pearl gouramis do.
Watch outBlack ghost knives are much bigger and pushier than pearl gouramis, 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 pearl gouramis.

What works

Both are fine at 77–82°F.
pH 6–7.5 suits both.
They use different parts of the tank: pearl gouramis the top, 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

	Pearl gourami	Black ghost knife
Temperature	77–82 °F	73–82 °F
pH	6–7.5	6–8
Adult size	5.0 in	15.0 in
Minimum tank	30 gal	125 gal
Temperament	Peaceful	Semi-aggressive
Swims at	Top	Bottom
Group	Alone or in pairs	One per tank
Diet	Omnivore	Carnivore

Better tank mates for pearl gouramis

All pearl gourami tank mates

Better tank mates for black ghost knives

All black ghost knife tank mates

Questions

Can pearl gouramis live with black ghost knives?

No. Pearl gouramis and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 5 inches pearl gouramis do.

What temperature suits both pearl gouramis and black ghost knives?

77–82 °F. Pearl gouramis need 77–82 °F, black ghost knives need 73–82 °F.

What size tank do pearl gouramis and black ghost knives need together?

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