"tuxedo" molly may actually be a platy/platy cross?

[sp00f]

I'm starting to wonder if my molly is actually a molly. She's been in tanks with males several times, both at the store and my house, and has never been pregnant - the males I've had don't even pursue or seem interested in her even though she pesters them for attention. She's also slightly smaller / more vertically compressed than my other female and has her dorsal fin in a different location. She's "tuxedo" colored, which I've only ever seen in platys before. I hear mollies and platys can't cross-breed, so while I initially thought she might be some sort of mule, she may just be a rather large platy - anyone know how to tell for sure? The other female is pregnant yet again, and it made me start wondering why the tuxedo's never had babies.

edit: here's a photo, the top one's definitely a female molly, the mystery fish is on the bottom left. See the major difference in dorsal fin size/shape? Her head is also a slightly different shape.

[Only Registered Users Can See Links.]

[Little Embers]

Doesn't look like a Molly to me, but these days :shrug: ! Could also possibly be a female swordtail, or a platy/swordtail cross. With all the continuous crossbreeding between these two, it can now be difficult to tell just from body shape alone.

[sp00f]

lol - she was sold to me as a molly but never bred, I guess she's just an imposter. She gets along fine with the others, though, I guess she thinks she's a molly too.