Real dwarfs, like Cherubs, are usually (emphasis on USUALLY) reef-safe. Mine was fine with softies, anemones & LPS. They're small, brilliantly coloured & with lively personalities. Cherubs are my fav. dwarf angel (as if you couldn't tell by all this gushing
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Slightly larger ones like Coral Beauties and Bi-colours are more of a risk. If you want to take a chance, go small & maybe try it with some xenia or other tempting tidbit before releasing it into a reef tank where it will be near impossible to catch again if it doesn't work out. Maybe in a QT or sump/refugium?
As with all spp., it will mostly depend on the temperament of that particular fish. I was told that no fish eat Prolifera macroalgae, but one of mine did & he/she taught the others to do it as well, so now I have no Prolifera left in my main tank
JMO
Anthony