Can black ghost knives live with tinfoil barbs?

Verdict
Yes

Yes. Black ghost knives and tinfoil barbs make a good pair. Both are fine at 73–80°F. Plan on at least 125 gal.

Black ghost knifeBlack ghost knife73–82°F · pH 6–8 Tinfoil barbTinfoil barb72–80°F · pH 6.5–7.5

Why it works

Water side by side

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

Size to scale

Black ghost knife · 15 inTinfoil barb · 12 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 knifeTinfoil barb
Temperature73–82 °F72–80 °F
pH6–86.5–7.5
Adult size15.0 in12.0 in
Minimum tank125 gal125 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomMiddle
GroupOne per tankGroups of 5+
DietCarnivoreOmnivore

Better tank mates for black ghost knives

All black ghost knife tank mates

Better tank mates for tinfoil barbs

All tinfoil barb tank mates

Questions

Can black ghost knives live with tinfoil barbs?

Yes. Black ghost knives and tinfoil barbs make a good pair. Both are fine at 73–80°F. Plan on at least 125 gal.

What temperature suits both black ghost knives and tinfoil barbs?

73–80 °F. Black ghost knives need 73–82 °F, tinfoil barbs need 72–80 °F.

What size tank do black ghost knives and tinfoil barbs need together?

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