I have a Matted Filefish that I move between two tanks and it does a GREAT job of wiping out Aptasia. Other types of filefish are definate coral munchers, and some people have had problems with Matted filefish eating coral - but I have had good luck with this one.
When first purchased, over a year ago, I had a large aptasia infestation that the filefish cleared out in a few months. I also suspect that it nipped at one colony of Yellow Polyps, but not enough to cause extensive damage. It has never bothered any of our LPS coral, but I do not keep a lot of SPS and do not know if it would bother them.
Aside from the benefit of aptasia control, it is simply a cool fish. It floats thru the tank using transparent fins that are virtually invisible, and is able to change colors. Non-aggressive, it gets along with anything in the tank.