Thanks both of you for your fast replies. They were both encouraging.

I had not though about how I would acquire the hybrids too much. I knew it might be hard to find them and that I may have to try and sex RES and BG (only one sec of each type in the pond) to try and force the first generation to become hybrids.

Perhaps stocking 100 of each RES and BG would be a good idea so that the RES could both learn from the BG and have the change to naturally hybridize?