Can crayfish live with mollies?

Verdict
Yes

Yes, crayfish and mollies can live together. Both are fine at 72–77°F. Plan on at least 20 gal.

CrayfishCrayfish65–77°F · pH 6.5–8 MollyMolly72–82°F · pH 7.5–8.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–77°Crayfish 65–77°Molly 72–82°
The green band is the temperature range both can live in.
456789Both: 7.5–8Crayfish 6.5–8Molly 7.5–8.5
The green band is the pH both tolerate.

Size to scale

Crayfish · 5 inMolly · 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

CrayfishMolly
Temperature65–77 °F72–82 °F
pH6.5–87.5–8.5
Adult size5.0 in4.0 in
Minimum tank20 gal20 gal
TemperamentAggressivePeaceful
Swims atBottomTop
GroupOne per tankGroups of 3+
DietOmnivoreOmnivore

Better tank mates for crayfish

All crayfish tank mates

Better tank mates for mollies

All molly tank mates

Questions

Can crayfish live with mollies?

Yes, crayfish and mollies can live together. Both are fine at 72–77°F. Plan on at least 20 gal.

What temperature suits both crayfish and mollies?

72–77 °F. Crayfish need 65–77 °F, mollies need 72–82 °F.

What size tank do crayfish and mollies need together?

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