They should do fine, but still watch them incase. I have two 2" crayfish with my 13" aro, 2 4"+ pbass and a pleco. They haven't done anything to each other, yet.
I have bought a pound or so of the large live crayfish at the grocery that people eat. Anyways, I decided to see what happens and I put some in my tank. These crayfish werre huge too. Anyways, my pbass made short work of them...and looked at me with their tails swishing back and forth as if to say "got any more???"
