Can bettas live with hatchetfish?

Verdict
Yes

Yes. Bettas and hatchetfish get along in the same tank. Both are fine at 76–81°F. Plan on at least 20 gal.

BettaBetta76–82°F · pH 6.5–7.5 HatchetfishHatchetfish75–81°F · pH 5.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–81°Betta 76–82°Hatchetfish 75–81°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Betta 6.5–7.5Hatchetfish 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Betta · 2.5 inHatchetfish · 1.5 in0"1"2"3"4"5"6"
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

BettaHatchetfish
Temperature76–82 °F75–81 °F
pH6.5–7.55.5–7.5
Adult size2.5 in1.5 in
Minimum tank5 gal20 gal
TemperamentSemi-aggressivePeaceful
Swims atTopTop
GroupOne per tankGroups of 6+
DietCarnivoreCarnivore

Better tank mates for bettas

All betta tank mates

Better tank mates for hatchetfish

All hatchetfish tank mates

Questions

Can bettas live with hatchetfish?

Yes. Bettas and hatchetfish get along in the same tank. Both are fine at 76–81°F. Plan on at least 20 gal.

What temperature suits both bettas and hatchetfish?

76–81 °F. Bettas need 76–82 °F, hatchetfish need 75–81 °F.

What size tank do bettas and hatchetfish need together?

At least 20 gal, set by the hatchetfish. Add space for each extra fish.