The photo is of a pair of Poeciliopsis gracilis, the porthole livebearer, male right and female left.
We acquired our starting breeders of this species from Rusty Wessel in 2008. Rusty collected the fish from Rio Copan in Honduras. I recently wrote a column about them for Tropical Fish Hobbyist. It’s a nice peaceful little livebearer with a unique color pattern.
The genus Poeciliopsis has 21 valid species found primarily in Mexico. One species, P. occidentalis, the Gila topminnow, is found in Arizona and New Mexico. It’s endangered and can’t be collected. That’s a shame since the males are red and black.