Can flowerhorns live with black ghost knives?

Verdict

Yes, with care

Yes, with care. Flowerhorns and black ghost knives can share a tank, but watch one thing. Flowerhorns are aggressive. Black ghost knives hold their own only in a big tank with places to hide.

Flowerhorn80–89°F · pH 7–8

Black ghost knife73–82°F · pH 6–8

What to watch

Watch outFlowerhorns are aggressive. Black ghost knives hold their own only in a big tank with places to hide.

What works

Both are fine at 80–82°F.
pH 7–8 suits both.
They use different parts of the tank: flowerhorns 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

	Flowerhorn	Black ghost knife
Temperature	80–89 °F	73–82 °F
pH	7–8	6–8
Adult size	12.0 in	15.0 in
Minimum tank	75 gal	125 gal
Temperament	Aggressive	Semi-aggressive
Swims at	Middle	Bottom
Group	One per tank	One per tank
Diet	Carnivore	Carnivore

Better tank mates for black ghost knives

All black ghost knife tank mates

Questions

Can flowerhorns live with black ghost knives?

Yes, with care. Flowerhorns and black ghost knives can share a tank, but watch one thing. Flowerhorns are aggressive. Black ghost knives hold their own only in a big tank with places to hide.

What temperature suits both flowerhorns and black ghost knives?

80–82 °F. Flowerhorns need 80–89 °F, black ghost knives need 73–82 °F.

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

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