I'm afraid that all the existing hybrids within the genera Poecilia and Xiphophorus (except, I believe, molly/guppy crosses) are fertile - most of the mollies, swordtails and platys you see are in fact hybrids.I fully respect your beliefs.If the slim chance that any offspring are produced, the will not leave my home, nor will they be intruduced into my fish community. I highly doubt they will be able to reproduce when adults. At least with mammal hybrids, we see that they are born sterile, as in the mule which is XX Horse, XY donkey. Or a hinny, xx donkey xy horse. Aslo, there is the liger and the tigon.
Thank you everyone for your thoughts.
Don't take this the wrong way, but I think you need to do a lot more research into these fish before you start mucking them around intentionally.