Actually not so slow, in the first pic, mine were less than 0.5", and in 3 months they have more than doubled in size. I consider that not to bad, especially with over 20 individuals in the same tank all producing pheromones at the same time.
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.