I kept one about 15 yrs ago, beautiful fish was extremely picky eater and I think it I only got it to eat 2-3 times, eventually it died from lack of food it seemed, fish never would take food, I had heard that was a issue with trying to kept and I was probably 17 at the timeI normally do freshwater, but my dream fish has always been the Moorish Idol. Definitely in a school in a FOWLR type setup.
I'm leery of ever attempting it because of the expense involved and the many poor outcomes I've heard about keeping them.