Don't think I have ever seen so much misinformation in a thread likely mostly from people that "heard" but never actually owned angels. Probably not in a frag tank but I have kept dwarf angels in soft, mixed and sps reefs for 30+ years. In the 200g mixed I have now I have flame, flameback, potters, bicolor, multicolor. Most places list them as reef safe with caution but other than occasionally nipping at corals they don't bother my LPS, SPS, shrooms, ricordia or zoas. If anything the hardest part about them is getting a group that is not attacking each other. They may eat sponge in the wild but they certainly don't require a sponge diet and spend most of the time grazing like a tang. All my fish live off mysis, nori, spirulina flakes, prime reef flakes, spectrum pellets and are extremely fat and healthy. In my experience they are far hardier than most fish especially tangs. Really wish they would eat sponge as I'm having a black sponge problem.