Looks a bit tiny/skinny to be an endler, but it's hard to say from the pics. An unhatched egg would have a much easier time surviving the journey dry(ish) than fry would, so I'd go with some sort of egglayer fry. Loving the scape!
That makes sense. I have noticed a bit of green or blue in its eye and behind its gills. Doesn't seem like endler coloration. I snapped a few blurry pics last night and will post them when I get home. The little guy is very hard to take a picture of, but maybe one of you experts can help with an id.
By the way inka, your goby tank is inspiring. Such cool looking fish and a great scape for them.