hmm..good points guys, and I'm not necessarily against cross-breeding rays...
I was just comparing to mbuna hobbyists that generally abhor hybrids,which usually are of the same genus. But then again, there is the lifespan difference that would keep the ray genepool stronger. I just wonder about the optimum future so many envision, when the overwhelming majority of fw rays sold are captive bred. How many folks will be selling identifiable species, vs. hybrid "potomotrygon sp.", each individual looking different.
It could end up being analogous to diamondback terrapin subspecies distribution along the eastern seaboard, which I'm way to lazy to explain unless anyone is interested.