Well, that information isn't entirely accurate. They're about as peaceful as some of the more docile Tangs, like Yellows, but not completely non-aggressive, especially not larger specimens. 125 is still probably too small, something more like a 6x3 or better 8 or more x 2 or more tank is more of a reasonable minimum. They do not naturally eat corals or polyps, but some individuals may pick, especially while foraging. better than 90% of the gut content of wild Idols is sponge, the rest algae. The problem isn't really feeding, I don't think. Idols that are eating will eat just about anything. Rather, I think it's more shipping and holding in bare tanks that freaks them out. They do not respond well to being transported/acclimated to new tanks at all, and once an Idol goes off food, which many do during shipping/transfer, it tends to stay off its food.