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Re: Molly Platy Hybrid Babies
That's a deformity.
All of the aquarium store Xiphophorus (swords, platies and variatus) are hybrids - mixes with each other. The least hybridized is variatus, but it has been used to add its oranges and reds to platies (maculatus) and swords (helleri). Many swords are smaller than wilds (5-6 inch fish) with platys and variatus genes, and often higher bodied from platy crosses. You can't honestly call a pet shop livebearer by a latin name - they are artificial hybrids rather than biological species now.
To complicate matters, it looks like X alvarezi swords from southern Mexico were mixed with central Mexican helleri to complicate the swordtail genetics more, These fish wouldn't meet in nature.
So you get a lot of weird genetics popping out, and forms like your little spotted guys appear by surprise. A male can fertilize a female in the pet store, and the babies will keep coming for months, as a single fertilization produces several broods. The females keep the sperm packets alive internally and refertilize themselves, as jrman pointed out.