How about a side clear view photo, preferably with a solid background?

I keep both normal and gold sport pure Endlers and the pure wild form, regardless if normal or a natural color sport, is pretty hard to confuse with an F-1 Domestic Gup x Endler's cross, but I've also seen F-2 and up crosses where the Endler looks so much like it's wild ancestor, it would take a DNA test to be sure.

A side view would really help but from the shot already shown it looks more like a guppy because of the tail. Every pure endler I have ever seen has a forked tail but it could be a hybrid.

Agreed. It could also be a wild, or F-1 Gup. I know a few Gup breeders who buy wild caught's to occassionally introduce into their domestic stock for outcross (can't really call it hybred) vigor.

But they have a near 99% cull rate and if they haven't any large fish of their own, dump them in bulk as feeders.