Too young to tell yet. They are hermaphoriditic, when they are born they are neither sex and as they mature the dominent one becomes female and grows larger, the other becomes male and stays a little smaller. The female cannot then change sex, but if the female dies, the male can change to female. Once it is female its stuck that way LOL
All in all a very interesting species. The closer of the two (white band all the way round the caudal pundacle) looks a little larger, so that may end up the female I call it Krusty (May need to change it in the future) and the other is Bob.
Jon