Can black ghost knives live with elephant nose fish?

Verdict
Yes

Yes, black ghost knives and elephant nose fish can live together. Both are fine at 73–82°F. Plan on at least 125 gal.

Black ghost knifeBlack ghost knife73–82°F · pH 6–8 Elephant nose fishElephant nose fish73–82°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 73–82°Black ghost knife 73–82°Elephant nose fish 73–82°
The green band is the temperature range both can live in.
456789Both: 6–7.5Black ghost knife 6–8Elephant nose fish 6–7.5
The green band is the pH both tolerate.

Size to scale

Black ghost knife · 15 inElephant nose fish · 9 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

Black ghost knifeElephant nose fish
Temperature73–82 °F73–82 °F
pH6–86–7.5
Adult size15.0 in9.0 in
Minimum tank125 gal55 gal
TemperamentSemi-aggressiveSemi-aggressive
Swims atBottomBottom
GroupOne per tankAlone or in pairs
DietCarnivoreCarnivore

Better tank mates for black ghost knives

All black ghost knife tank mates

Better tank mates for elephant nose fish

All elephant nose fish tank mates

Questions

Can black ghost knives live with elephant nose fish?

Yes, black ghost knives and elephant nose fish can live together. Both are fine at 73–82°F. Plan on at least 125 gal.

What temperature suits both black ghost knives and elephant nose fish?

73–82 °F. Black ghost knives need 73–82 °F, elephant nose fish need 73–82 °F.

What size tank do black ghost knives and elephant nose fish need together?

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