Moorish Idols have a very poor survival record in home aquariua. I do have one that I was talked into taking and fortunately it has survived for over a year in my aquarium. This is not the norm for these fish. I know that Deb had one that she recently lost that she got from SamW and it was another exception to the rule. In no way would I recommend these fish to anyone even though they are beautiful.
BTW I have never noticed mine eating aptasia but I do not have bubble algea in this tank so maybe that is why.

My Lucky Moorish Idol
 

I have sucessfully had my Idol for close to1-1/2 yrs. now & was maybe 7-9 months from the previous owner, & is my prize. He came from a 90 gal into my 72 bowfront which I copied the eating habits & have not had any problems.
Definetly does not eat Aptasia. Lazy B-------