They usually are able to breed once they get the the 1 inch to 1 and a half inches. The males are normally larger, their fins are more pointy, and they wont have much more color to them. The females will usually be a bit smaller, generally have rounded fins, and their stomach is normally a red or an orange. If you want you can post a picture of each one and myself or someone else can sex them for you. For someone who doesn't know how to sex them, the pink version will be harder to sex than the black version.