Damsel not reef safe?

Never heard of a Damsel eating coral. My guess would also be that the coral caught food and the damsel was trying to eat that. That happens from time to time with a lot of fish.

 

Damsels don't eat coral flesh. They eat meaty food or flakes. As John said, they might have been attempting to extract this from corals that just "scored." As far as reef safe goes, damsels are very reef safe. They are just unsafe to other fish. They can be a menace to the point where they simply bully other fish until they die.

Damsel fish won't hinder the health of corals, but they can hinder the health of other tank inhabitants; fish and invertebrates included.