My pink tail trigger is a model citizen, dosen't bother a thing. But he'd be a bit large for a 90 as mine is currently around the 8" in length area. He's in a 400G tank.
All fish can be possible coral pickers. They are each different, same as we are. Some are more tollerent than others. I do beleive though that if you keep them happy and well fed, they are less likley to nip at your prized corals.
