I've had a 2" powder blue tang that got fat and grew 1/2" in a few months and now, as well as being most aggressive, is the largest. It was added with a 2" yellow tang to a 120g reef tank that had only a small pair of clown-fish. My question is why does this fish only harass new additions that are bigger than it? So far, the pb tang has chased a newer fairy wrasse, lyretail anthias, and a fire goby(all 1-2") for a day or two, then warm up to each. However, last week when I freed a 4" linatus fairy wrasse from a 5 day acclimation box stay it was never left alone and I haven't seen it for a few days. Is this typical behavior for such an environment? Will this powder blue butt-head always be the largest fish in my peaceful tank?