I suppose if you found one in any different river, that river could be added to the name, so there are as many variants, as there are many rivers, lakes or lagoons in their range.
It's not so much a different physical or color variation, as simply a location variant where it is found.
I took a video in Cenote Aktun Ha, not connected by any other surface water river.
So if some were collected there, you might call them, Parachromis friedrichsthalii "Aktun Ha".
Here is the video, a mature female appears at about 1 minute, and juvies here and there throughout.