Can rams live with black ghost knives?

Verdict
No

No. Rams and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 2.5 inches rams do.

German blue ramGerman blue ram80–86°F · pH 5–7 Black ghost knifeBlack ghost knife73–82°F · pH 6–8

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 80–82°German blue ram 80–86°Black ghost knife 73–82°
The green band is the temperature range both can live in.
456789Both: 6–7German blue ram 5–7Black ghost knife 6–8
The green band is the pH both tolerate.

Size to scale

German blue ram · 2.5 inBlack ghost knife · 15 in0"2"4"6"8"10"12"14"
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

German blue ramBlack ghost knife
Temperature80–86 °F73–82 °F
pH5–76–8
Adult size2.5 in15.0 in
Minimum tank20 gal125 gal
TemperamentPeacefulSemi-aggressive
Swims atBottomBottom
GroupAlone or in pairsOne per tank
DietOmnivoreCarnivore

Better tank mates for rams

All german blue ram tank mates

Better tank mates for black ghost knives

All black ghost knife tank mates

Questions

Can rams live with black ghost knives?

No. Rams and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 2.5 inches rams do.

What temperature suits both rams and black ghost knives?

80–82 °F. Rams need 80–86 °F, black ghost knives need 73–82 °F.

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

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