Well, these must be amazingly rare, since I only see this type-
in closed systems. I still don't believe amphipods(the one pictured) eat healthy corals. I've not seen this, or heard of it in my short time in this hobby, and I still go out of my way to keep their population strong.
Of course they will eat coral, but not healthy coral IMO
My aptasia eating filefish-
does nothing but eats amphipods and copepods. He nipped at a few corals early on, but lost interest since.
Just an idea.