I typically feed my tank (fish and shrimp) and then wait awhile( 20 or 30 minutes) before turning my PH's back on so that my crabs (about 20 hermits and 2 emerald mithrax) can scavenge food off the bottom. And then I got to thinking....is this even necessary? Will they die if I don't? BTW, my mithrax's are getting huge, and I'm considering getting rid of them.