Can crayfish live with platies?

Verdict
Yes

Yes. Crayfish and platies make a good pair. Both are fine at 70–77°F. Plan on at least 20 gal.

CrayfishCrayfish65–77°F · pH 6.5–8 PlatyPlaty70–80°F · pH 7–8.2

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 70–77°Crayfish 65–77°Platy 70–80°
The green band is the temperature range both can live in.
456789Both: 7–8Crayfish 6.5–8Platy 7–8.2
The green band is the pH both tolerate.

Size to scale

Crayfish · 5 inPlaty · 2.5 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

CrayfishPlaty
Temperature65–77 °F70–80 °F
pH6.5–87–8.2
Adult size5.0 in2.5 in
Minimum tank20 gal10 gal
TemperamentAggressivePeaceful
Swims atBottomMiddle
GroupOne per tankGroups of 3+
DietOmnivoreOmnivore

Better tank mates for crayfish

All crayfish tank mates

Better tank mates for platies

All platy tank mates

Questions

Can crayfish live with platies?

Yes. Crayfish and platies make a good pair. Both are fine at 70–77°F. Plan on at least 20 gal.

What temperature suits both crayfish and platies?

70–77 °F. Crayfish need 65–77 °F, platies need 70–80 °F.

What size tank do crayfish and platies need together?

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