Can bichirs live with black ghost knives?

Verdict
Yes

Yes. Bichirs and black ghost knives get along in the same tank. Both are fine at 73–82°F. Plan on at least 125 gal.

BichirBichir72–82°F · pH 6.5–7.5 Black ghost knifeBlack ghost knife73–82°F · pH 6–8

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 73–82°Bichir 72–82°Black ghost knife 73–82°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Bichir 6.5–7.5Black ghost knife 6–8
The green band is the pH both tolerate.

Size to scale

Bichir · 12 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

BichirBlack ghost knife
Temperature72–82 °F73–82 °F
pH6.5–7.56–8
Adult size12.0 in15.0 in
Minimum tank75 gal125 gal
TemperamentSemi-aggressiveSemi-aggressive
Swims atBottomBottom
GroupAlone or in pairsOne per tank
DietCarnivoreCarnivore

Better tank mates for bichirs

All bichir tank mates

Better tank mates for black ghost knives

All black ghost knife tank mates

Questions

Can bichirs live with black ghost knives?

Yes. Bichirs and black ghost knives get along in the same tank. Both are fine at 73–82°F. Plan on at least 125 gal.

What temperature suits both bichirs and black ghost knives?

73–82 °F. Bichirs need 72–82 °F, black ghost knives need 73–82 °F.

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

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