A black molly will add much contrast to a tank. I would get a damsel domino, but it will not get along with the fish that I already have.I never really understood the desire to add mollies to reef tanks.....what is the main reason people are attempting? IMO, they don't look all that great compared to saltwater options.....they can't really handle strong flow......do they eat enough algae to say they are a better option than some of the smaller, algae eating saltwater fish? If so, I will take 5 lol.