The focus is not very sharp in any of them. I agree with cparka that the first one has potential, but it needs considerably more depth of field to get more of the coral in focus. The second shot is OK if it were in better focus overall and the frag plug wasn't showing. That air bubble needs to be cloned out as it's a major distraction. The third shot needs to be focused, brightened up and my guess is that the white balance is not right. Good angle and decent composition on the fourth shot, but it's unlikely your camera can deliver sufficient depth of field to make the shot work. The last shot has potential to be the best, by far, but, as cparka stated, the focus is on the back edge and not particularly sharp. If you could get considerably more depth of field and better focus on that one, it would be the standout of the bunch. Also, when shooting these, turn your flow off so feeding tentacles will be relatively still and you won't get particles causing streaks in the image.
Gary