Can black ghost knives live with arowanas?

Verdict

No. Black ghost knives and arowanas should not share a tank. An adult silver arowana eats fish that fit in its mouth, and at 15 inches black ghost knives do.

Black ghost knife73–82°F · pH 6–8

Silver arowana75–86°F · pH 6–7

What to watch

Deal breakerAn adult silver arowana eats fish that fit in its mouth, and at 15 inches black ghost knives do.
Deal breakerArowanas are aggressive and much bigger than black ghost knives.

What works

Both are fine at 75–82°F.
pH 6–7 suits both.
They use different parts of the tank: black ghost knives the bottom, arowanas the top.

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

	Black ghost knife	Silver arowana
Temperature	73–82 °F	75–86 °F
pH	6–8	6–7
Adult size	15.0 in	36.0 in
Minimum tank	125 gal	250 gal
Temperament	Semi-aggressive	Aggressive
Swims at	Bottom	Top
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 black ghost knives live with arowanas?

No. Black ghost knives and arowanas should not share a tank. An adult silver arowana eats fish that fit in its mouth, and at 15 inches black ghost knives do.

What temperature suits both black ghost knives and arowanas?

75–82 °F. Black ghost knives need 73–82 °F, arowanas need 75–86 °F.

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

At least 250 gal, set by the silver arowana. Add space for each extra fish.