Sorry, but you were close, its a platy. I don't recall the name of the color variation but I have a tank full of them. I think its tuxedo something but the something refers to the orange color. It is another type of livebearer as the molly is but instead of being in the poecilia family like a molly or a guppy it is in the xiphophorus family that includes platies, swords, what were called moons and what are called variatus. They are a nice fish that grows to about 2 inches and are very hardy in most circumstances. The picture is of a nice looking male.
Edit: typos