I had a cow fish in my reef back when I was in high school. Didn’t do any research just thought it was cool and got it. From what I remember it ate pellet food and none of my fish, including a six line and bicolor angel, bothered it. Don’t remember it nipping at corals. It lived a few months before it got wedged between a couple rocks. Died the next day. It was a fun fish, would “kiss” your finger when you put your hand on the glass.
Beautiful and fun fish to have, but they are a pain. Mine destroyed walls in my house next to the aquarium because it would spit water out of the tank whenever it saw me. It wanted food. They also grow so big.