I think butterflies eat/nip corals. But I don't know enough about them to really give you anything of value.
Most angels do as well. I can't give you anything on a species-by-species recommendation, but some of the dwarf angels are little less prone to nipping, though many of them can/will. I'd research more into dwarf angels and see what you come up with. Good luck!
125 gallon saltwater: 55gal sump, 4 Blue-Green Chromis, Purple Tang, True Perc, Firefish, Royal Gramma, 5 Ricordea, Bubble Coral, 15 Pulsing Xenia, Green Star Polyps, Deresa clam, Green-Tip Torch Coral (about 11 "heads"!), Orange Montipora Cap, Purple M. Digitata, Green Slimer Acro. Yongei, 3 Orange M. Digitata, Pink&Green Acro. Millepora