I had one very young plakat "girl" that we bought from Wal-Mart. The other girls stress striped like crazy and she was so aggressive we removed her after a few weeks of being in the big tank. We re-homed her to my neighbor along with a 10 gallon tank, so her boys could have a fish to take care of as our apartments don't allow any pets other than fish. I took her another round of plant clippings after she had her a few months and she was concerned because there were soapy bubbles on top of the water and every time she cleaned the tank, they came right back. I inspected "her" and she was absolutely a he! It was cute but it also explained the stress stripes on all my girls and why "she" didn't fit into the sorority.
I'd bet this is a boy fish, that tail just looks like a young veiltail to me. Do we have any breeders that breed veiltails on the forums? Maybe they could answer you a bit more than "i think" lol Maybe Chard56, I think I remember a picture of some veiltails he posted awhile back.