There was a post a little while back asking for experiences with Endlers and I put my story on there, but Maybe it wouldn't hurt to repeat a little of it.
I sort of got my first endler by mistake. They didn't tell me what it was, only that I had to pay more than the regular guppy price for him. I think they said he was a special type of guppy. He was in a tank full of guppies, so they weren't trying too hard to keep the strain pure there. Then when he seemed to have trouble with the food I was feeding my other guppies, I thought maybe he was just very young. (I had no fry of my own yet.) I isolated him and went out and bought some powder type fry food. He was doing great pretty soon, and before i knew if they could interbreed, they proved they could, so I wasn't messing with them on purpose in the first place, but I do like the results.
I'm not sure if my "guplers" (as I like to call them) have bred, but there's a good chance they have, especially since about half of my males are about the size of Endlers and have their temperment and some wierd tail shapes, but are collored just like one of my male guppies, who is long gone now, and my most recent fry turned out to look like endlers, even though Tiger, the Endler who started it all, died about a year ago.
When I got the baby food for Tiger I looked through a big book that one of the guys at the store got out to try to figure out what kind of fish Tiger could be, and the guy and the book seemed pretty clueless, but later I found a few critters that looked just like Tiger at a different store and figured out what he was.