My sixline harassed my flame angel. ended up stressing him to death. anyways, i believe most of the wrasses that belong to the Pseudocheilinus family end up getting aggressive as they mature. I had a Mystery Wrasse that was the most peaceful fish when he was small, as he grew he became aggressive. Like I said, the wrasses belonging to that family end up getting to be aggressive as they mature, but all fish are different. I'm just speaking from my experience. If he gets or is aggressive, just put him in time-out in the sump lol.