I have a pair of these. I got them together, hoping one would either be dominant already or would become dominant and it seems to have worked. I think the one I call dominant is the male. There is very little difference in color between them. My "female" has more tiny black dots on her body (in addition to the pink and orange striping). I don't see this on yours and maybe it just coincidental on mine. Also, a weird thing: My "male" is what I would call pink with orange stripes and the "female" is orange with pink stripes. I know you are going to ask me how I tell between background color and stripes and my answer is that the stripes are narrower; thus the "male" is pinker. I can see no difference in how much blue either of them has and this is supposed to be a gender difference.
In the evenings, after their dinner, but before lights out, the "male" gets all excited and displays to the "female" and his colors change so that he has very light whitish vertical stripes on his body. He can change back and forth between no vertical stripes and having some in an instant. I like these fish a lot.