Hasn't touched one. I got this fish b/c my friend had a very large one in his 150 and it kept he algae in control and his tank was Insane with SPS, Lps, Zoas, and pretty much anything you could think of. I'm talking corals growing out of his tank and his never touched anything either. It is a rabbitfish though and there is an inherent risk involved. Mine is great I wouldn't get rid of it for the world.