Do they display any symptoms when they are about to molt? He has been digging alot in the gravel bed lately. He has dug out the gravel in my tank all the way down to the under gravel filter that I have under a large rock structure. I pushed the gravel back and he dug it out once again today. Is he trying to secure himself a little spot so that he can molt? What other symtoms do molting Blue Crayfish display?