Byrd

is there such a thing as a livebearer crossbreed?

Chief_waterchanger

Mollies can crossbreed with guppies. (Both are of the poecilia genus.) The cross between molly and guppy is always sterile (not able to produce fry of their own) and are, in my opinion, ugly. They've been called Muppy or Golly, but are primarily called Muppy.

Most swordtails and platies are crosses between between a mix of different xiphophorus species. (It just depends on the species as to what they can cross with.)

Not all poecilia can crossbreed within their genus, just as not all xiphophorus (swordtails/platies) can crossbreed within their own genus. To my knowledge crossing between two different genera (plural of genus) is genetically impossible. The very definition of genus would indicate that it is not possible for 2 different genera to cross.

Interesting article on this topic in the latest issue of ALA newsletter. (ALA = American Livebearer Association)

Butterfly

Guppys and Endlers will cross breed. Although Endlers are going extinct in their natural habitat it is not advised to dilute their genes with Guppys.
Platys and Swordtails will crossbreed.
All of those are livebearers
Carol