Your goniopora will slowly get smaller and smaller. They don't like to get beat down like that. I know I have a gonio and 2 perc clowns and about 10 months ago the gonio was about the size of a softball, now it is the size of an orange. Try moving it around, it confused my clowns. The one would go back to the spot and hover. They found it later but don't seem do dive into it and nestle like a pig in @#$%.
I've tried a couple of anenomes, but they don't care.
I might try a green carpet if I see one.