Can crayfish live with rummy nose tetras?

Verdict
Yes

Yes, crayfish and rummy nose tetras can live together. Both are fine at 75–77°F. Plan on at least 20 gal.

CrayfishCrayfish65–77°F · pH 6.5–8 Rummy nose tetraRummy nose tetra75–84°F · pH 5.5–7

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–77°Crayfish 65–77°Rummy nose tetra 75–84°
The green band is the temperature range both can live in.
456789Both: 6.5–7Crayfish 6.5–8Rummy nose tetra 5.5–7
The green band is the pH both tolerate.

Size to scale

Crayfish · 5 inRummy nose tetra · 2 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

CrayfishRummy nose tetra
Temperature65–77 °F75–84 °F
pH6.5–85.5–7
Adult size5.0 in2.0 in
Minimum tank20 gal20 gal
TemperamentAggressivePeaceful
Swims atBottomMiddle
GroupOne per tankGroups of 6+
DietOmnivoreOmnivore

Better tank mates for crayfish

All crayfish tank mates

Better tank mates for rummy nose tetras

All rummy nose tetra tank mates

Questions

Can crayfish live with rummy nose tetras?

Yes, crayfish and rummy nose tetras can live together. Both are fine at 75–77°F. Plan on at least 20 gal.

What temperature suits both crayfish and rummy nose tetras?

75–77 °F. Crayfish need 65–77 °F, rummy nose tetras need 75–84 °F.

What size tank do crayfish and rummy nose tetras need together?

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