ANGELS: I'd say a small angel is probably safe with zoos and rics, but the minute there's acropora, he's liable to discover they're edible. Most softies, if you handle them, make your hands smell not so good, which probably argues for how they taste. Acros don't leave that scent, they're alive, and they just may smell good to angels, who in the wild make their living by cruising down the reef taking a piece of this and that coral. in the reef, it may even be a useful habit to the coral.
unfortunately in our tanks, they reach the wall and start over again. And again.
This goes for many nippers. in the reef, no problem, in our tanks, big problem.
And big angels, parrots, filefish, etc. do big damage fast.