I have no idea about the toadstool spliting, the line has always been present.
Also, while the anthia eats like a whale, he does not seem to make much of a mess.
what makes the most mess is the copperband as he only eats the bodies of the mysis and leaves the heads. So all you see in my tank after feeding time are a bunch of eyes floating around the tank (which can't be too good for water quality)
otherwise, both the anthia and copperband are only a month old in my tank. And the anthia just started coming out of the rocks permanently last week.