Depends on what kind of corals you keep. Any hard corals would likely get munched, and just about everything is risky. I keep mushrooms and leathers successfully (thus far) with my Angels. The older the Angel gets the more likely they seem to be to go after corals.....BTW, not sure how big your tank is, but Korans get very large, I would say a 150 would be a good minimum for this fish long term.