It's not hard to spawn them. The problem is that the eggs don't hatch, giving the false impression that the males are usually infertile. I knew this was not the case because I've bred super red males with gold females, and I did get fry.
I don't think they are on MFK so there's no thread... I've seen their fry together with some golds in the same tank, and they were obviously red.
I don't want to be secretive or anything, but I didn't figure this out and it would be wrong for me to leak it.