My maroon cown has started to stir up the sand by shaking his body really fast therefor pushing out the sand leaving big holes. I'am affraid the holes might lead to a collapse of my reef. Why is he doing that, is it beacause he need an anemone or what?
All the others are correct it is normal for your clown to do this and I think the post about nest building is probably the closest to the actual reason why.