Hi Hugues,
I’m not experienced at crossbreeding Paros, but I assume that hybridization of closely related species (e.g. the Harveyi-Group) is of course possible, and perhaps also happening in nature, where different species get in contact at some sort of borderline. I get to this point, because especially the members of this group don’t only show similarities in colour-patterns, but also in courtship behaviour and mood-related colouration… So why shouldn’t it be possible. As far as I remember, someone from the IGL-Forum has already bred hybrids accidently a few years ago. But it could also have been somewhere else…
These crossbreeding experiments that you talk of, could be interesting to confirm the status of some species, but the problem is: of course, classically, hybrids between two species should show decreased fertility or even be sterile, but I’m not so sure if this also applies to fish, especially closely related Paro species that vary only slightly in small colouration details. I think they could produce fertile offspring, why not?
Problems with fertility could also occur some generations later, so it would take very long to get results and it would furthermore not be clear if the infertility is a result of the cross- or the in-breeding afterwards.
So, since I don’t even have enough tanks for all the different species and forms I’d like to breed, I’ve not started such experiments yet 😆 .
Martin