...like a lot of reef fish like leopard wrasses, most butterflies. You can get plenty of nasties from the water just on a frag plug or rock so unless you QT your coral, then no tank is 100% parasite free.
I cannot believe that nobody linked this:
http://www.reefkeeping.com/issues/2002-12/fm/
I cannot believe that nobody linked this:
http://www.reefkeeping.com/issues/2002-12/fm/