Can black ghost knives live with kissing gouramis?

Verdict
Yes

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

Black ghost knifeBlack ghost knife73–82°F · pH 6–8 Kissing gouramiKissing gourami72–82°F · pH 6–8

Why it works

Water side by side

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

Size to scale

Black ghost knife · 15 inKissing gourami · 10 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 knifeKissing gourami
Temperature73–82 °F72–82 °F
pH6–86–8
Adult size15.0 in10.0 in
Minimum tank125 gal55 gal
TemperamentSemi-aggressiveSemi-aggressive
Swims atBottomMiddle
GroupOne per tankAlone or in pairs
DietCarnivoreOmnivore

Better tank mates for black ghost knives

All black ghost knife tank mates

Better tank mates for kissing gouramis

All kissing gourami tank mates

Questions

Can black ghost knives live with kissing gouramis?

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

What temperature suits both black ghost knives and kissing gouramis?

73–82 °F. Black ghost knives need 73–82 °F, kissing gouramis need 72–82 °F.

What size tank do black ghost knives and kissing gouramis need together?

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