One of my fav fish. First one didnt make it so am on my second now. All from LFS. First one I came across by chance. Second one i had to wait for a little while. My LFS has a notify list so they let me know as soon as they had one.
As the other posters stated, all fish are different. My first one was really peaceful. Didnt bother anyone and just went about his business. Never bothered any inverts. My second one is now the most aggressive fish in my tank. Not too bad but likes to show he is boss. I have seen him eat a snail but that was only after my hermit crab killed it for its shell. After the hermit tore the snail out, the radiant (and all my other wrasses as well) went to town on the dead snail. Other than that, have had no other instances. I have blood shrimps, cleaner shrimps, hermits, snails and clams in my tank. Haven't seen him bother anything else.