I am a breeder of wild type endlers livebearers. Although they are related to guppies about as closely as swordtails are related to platies, they are a distinctly non-guppy species. Many of the fish available at your local fish shop will indeed be crosses between guppies and endlers, in much the same way as the colorful swordtails at the shop are really crosses between wild swordtails and platies. I keep my species maintenance colonies in water at 77F, 25C. My water is fairly hard and I feed a flake that is high in vegetable matter. My own colony is in a 45 gallon show tank but a small colony could be maintained in about 5 gallons, 20 litres, of water. Sexing wild type endlers is even easier than sexing guppies. Because no female endler ever shows any color other than the base grayish color, any fish with any splash of color is a male.
If you have a pet shop variety, like tiger endlers for instance, you will need to examine the fish for a gonopodium vs. a triangular anal fin, just like any typical livebearer. We have a gender determination thread at the top of this section that will let you sex them with ease. Please be aware that tiger endlers are not endlers at all, they are guppy/endler hybrids.