Coral Safe or Not Coral Safe?

[The Grizz]

How do I know if a fish is coral safe. I have see several fish that I would like to have such as angel's and butterflies. But when I look them up they say "Coral Safe - NO", and I have seen them in reef tanks. What's the deal.

I have LPS, SPS, Softies, Mushrooms, Xenia, Zoe's, Gorg's and a sponge that I will be dividing up between both side's of my 155.

Would also like to add other corals that I don't have like Ricordia and birds nest.