Can crayfish live with upside down catfish?

Verdict
Yes

Yes. Crayfish and upside down catfish get along in the same tank. Both are fine at 72–77°F. Plan on at least 30 gal.

CrayfishCrayfish65–77°F · pH 6.5–8 Upside down catfishUpside down catfish72–79°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–77°Crayfish 65–77°Upside down catfish 72–79°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Crayfish 6.5–8Upside down catfish 6–7.5
The green band is the pH both tolerate.

Size to scale

Crayfish · 5 inUpside down catfish · 4 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

CrayfishUpside down catfish
Temperature65–77 °F72–79 °F
pH6.5–86–7.5
Adult size5.0 in4.0 in
Minimum tank20 gal30 gal
TemperamentAggressivePeaceful
Swims atBottomBottom
GroupOne per tankGroups of 3+
DietOmnivoreOmnivore

Better tank mates for crayfish

All crayfish tank mates

Better tank mates for upside down catfish

All upside down catfish tank mates

Questions

Can crayfish live with upside down catfish?

Yes. Crayfish and upside down catfish get along in the same tank. Both are fine at 72–77°F. Plan on at least 30 gal.

What temperature suits both crayfish and upside down catfish?

72–77 °F. Crayfish need 65–77 °F, upside down catfish need 72–79 °F.

What size tank do crayfish and upside down catfish need together?

At least 30 gal, set by the upside down catfish. Add space for each extra fish.