Fish that eat aptasia and/or bubble algae?

[Darksky]

Big Al's has some Emerald Crabs in now. They had some one of about 1" in diameter on Friday and had some smaller , 1/2 " ones today. I got one of the larger ones, as I didn't see the smaller ones at the time, to try and get rid of my bubble algea. It has only been in my tank a couple of days, but I have seen it eating some bubble algea already. It was funny to watch it try and pull one off the rock. When it finally came free, the crab almost fell over backwards.