Can crayfish live with cardinal tetras?

Verdict
Yes, with care

Yes, with care. Crayfish and cardinal tetras can share a tank, but watch one thing. They only share 76–77°F. Keep the heater set there and steady.

CrayfishCrayfish65–77°F · pH 6.5–8 Cardinal tetraCardinal tetra76–84°F · pH 4.6–7

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–77°Crayfish 65–77°Cardinal tetra 76–84°
The green band is the temperature range both can live in.
456789Both: 6.5–7Crayfish 6.5–8Cardinal tetra 4.6–7
The green band is the pH both tolerate.

Size to scale

Crayfish · 5 inCardinal 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

CrayfishCardinal tetra
Temperature65–77 °F76–84 °F
pH6.5–84.6–7
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 cardinal tetras

All cardinal tetra tank mates

Questions

Can crayfish live with cardinal tetras?

Yes, with care. Crayfish and cardinal tetras can share a tank, but watch one thing. They only share 76–77°F. Keep the heater set there and steady.

What temperature suits both crayfish and cardinal tetras?

76–77 °F. Crayfish need 65–77 °F, cardinal tetras need 76–84 °F.

What size tank do crayfish and cardinal tetras need together?

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