Can black ghost knives live with silver dollars?

Verdict

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

Black ghost knife73–82°F · pH 6–8

Silver dollar75–82°F · pH 5–7

What to watch

Deal breakerAn adult black ghost knife eats fish that fit in its mouth, and at 6 inches silver dollars do.

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, silver dollars the mid.

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 dollar
Temperature	73–82 °F	75–82 °F
pH	6–8	5–7
Adult size	15.0 in	6.0 in
Minimum tank	125 gal	75 gal
Temperament	Semi-aggressive	Peaceful
Swims at	Bottom	Middle
Group	One per tank	Groups of 5+
Diet	Carnivore	Herbivore

Better tank mates for black ghost knives

All black ghost knife tank mates

Better tank mates for silver dollars

All silver dollar tank mates

Questions

Can black ghost knives live with silver dollars?

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

What temperature suits both black ghost knives and silver dollars?

75–82 °F. Black ghost knives need 73–82 °F, silver dollars need 75–82 °F.

What size tank do black ghost knives and silver dollars need together?

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