So it looks like a darter tetra? Little confused if you mean it looks like the pic or it's actually green?
Similar to the pic you posted, maybe it's a Black Darter Tetra (Poecilocharax Weitzmani)
or from the green description you gave, maybe a Green Darter Tetra (Ammocryptocharax Elegans)
Or maybe it's one of the Etheostoma darters:
banded darter (Etheostoma zonale)
orangethroat darter (Etheostoma spectabile)
rainbow darter (Etheostoma caeruleum)
greenside darter (Etheostoma blennioides)
swamp darter (Etheostoma fusiforme)
Tangerine darter (Percina aurantiaca)?
lol...cmon has to be one of these.
There's actually a ton more, but some are specific locality and don't match the description.