Can crayfish live with black neon tetras?

Verdict
Yes

Yes. Crayfish and black neon tetras make a good pair. Both are fine at 73–77°F. Plan on at least 20 gal.

CrayfishCrayfish65–77°F · pH 6.5–8 Black neon tetraBlack neon tetra73–81°F · pH 5.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 73–77°Crayfish 65–77°Black neon tetra 73–81°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Crayfish 6.5–8Black neon tetra 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Crayfish · 5 inBlack neon tetra · 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

CrayfishBlack neon tetra
Temperature65–77 °F73–81 °F
pH6.5–85.5–7.5
Adult size5.0 in1.5 in
Minimum tank20 gal15 gal
TemperamentAggressivePeaceful
Swims atBottomMiddle
GroupOne per tankGroups of 6+
DietOmnivoreOmnivore

Better tank mates for crayfish

All crayfish tank mates

Better tank mates for black neon tetras

All black neon tetra tank mates

Questions

Can crayfish live with black neon tetras?

Yes. Crayfish and black neon tetras make a good pair. Both are fine at 73–77°F. Plan on at least 20 gal.

What temperature suits both crayfish and black neon tetras?

73–77 °F. Crayfish need 65–77 °F, black neon tetras need 73–81 °F.

What size tank do crayfish and black neon tetras need together?

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