Can crayfish live with hatchetfish?

Verdict
Yes

Yes. Crayfish and hatchetfish get along in the same tank. Both are fine at 75–77°F. Plan on at least 20 gal.

CrayfishCrayfish65–77°F · pH 6.5–8 HatchetfishHatchetfish75–81°F · pH 5.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–77°Crayfish 65–77°Hatchetfish 75–81°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Crayfish 6.5–8Hatchetfish 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Crayfish · 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

CrayfishHatchetfish
Temperature65–77 °F75–81 °F
pH6.5–85.5–7.5
Adult size5.0 in1.5 in
Minimum tank20 gal20 gal
TemperamentAggressivePeaceful
Swims atBottomTop
GroupOne per tankGroups of 6+
DietOmnivoreCarnivore

Better tank mates for crayfish

All crayfish tank mates

Better tank mates for hatchetfish

All hatchetfish tank mates

Questions

Can crayfish live with hatchetfish?

Yes. Crayfish and hatchetfish get along in the same tank. Both are fine at 75–77°F. Plan on at least 20 gal.

What temperature suits both crayfish and hatchetfish?

75–77 °F. Crayfish need 65–77 °F, hatchetfish need 75–81 °F.

What size tank do crayfish and hatchetfish need together?

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