Platy confusion--aggression b/t X. maculatus and variatus?

[LeahK]

The mojo's not working in my husband's tank. It's a 10g with three female platies. Two we bought as "tuxedo platies." The third is a "marigold platy." The tuxedos get along fabulously with each other, but they pick on the marigold constantly. The poor thing hides in the plants all day long. We're going to have to do some rearranging or rehoming to bring peace back to the tank.
I'm trying to figure out if the difference between tuxedos and marigolds is one of color variation only, or of species. Maybe there's aggression because we've got two different species in the tank. But this has been hard to figure out, because from what I see online both X. maculatus and X. variatus come in "tuxedo" varieties. Can anyone tell me if our platies are the same species or not?

Here's some pics.
In this one the marigold is in front and the tuxedo is behind it:

And here's how the tank usually looks, with the two tuxedos out front and the marigold hiding back in a corner:

The tank's been set up over a year now, cycled, well-planted, nitrates below 20.

 

[KarlTh]

I doubt the species difference makes much difference; I suspect that many colour varieties are hybrids between the two anyway.

 

[OldMan47]

Aquarium platies have been bred from variatus and other Xiphophorus. They are no longer a particular species that would be associated with a wild fish at all. Many common aquarium platies include some crosses to swordtails in their background. It is often the swordtail content that determines how aggressive they are. A wild type swordtail, X. helleri, is a more aggressive fish than a typical wild variatus. Color strains of aquarium platies are basically the same fish with different breeding backgrounds and differing breeders programs to fix the colors.

 

[jlink17]

How big is the tank? You may need to put them in a bigger tank so the nonaggressive one can have room to swim without worrying about the others chasing her. Sometimes you may have one female that is the dominant and they are just more aggressive towards others. I have found that my platy always do better in equal numbers as none are a "third wheel" and get picked on that way.