I have a crayfish in my aqurium. I was worried that I wasn’t feeding it the right stuff. May last two crayfish haven’t done too well. They usaully end up being fish food. Apparently crayfish will eat just about anything though:
“Your crayfish will eat just about anything. We typically feed ours large flake fish food and occasionally a small cut up potato or carrot. We have also heard of people feeding them Purina cat chow and occasionally egg shells (egg shells may help the crayfish out after the molting process by supplying needed calcium to help harden their exoskeleton).”
http://crayfish.byu.edu/faq.htm
I think they also like leafs alot… I am going to check more on this. I think they like the bacteria and fungi on decomposing leaves…