Hi:
they could care less about corals, so yes they are reefsafe.....HOWEVER I would consider them reef limiting. In that they will eat any other moving item they can fit into their cavernous mouth. Consider anyfish equal to or slighty larger than their body as food. Anything that moves will be sytematically eaten. A problem is that many fish will pick on the skin of these fish, since it looks like algae, so i don't what to tell you.
These fish are fantastic for species-only tanks.
frank