Ryan,
I looked at the e-mail pictures that Bz sent and his fish appear to have different genetics than the GG's in the experiment. I'm certainly no expert, but to my eyes they have different genetics independent of color differences.
Climate differences make for different growth rates, but it was surprising to me to see the winter GG growth rates in my experiment. It was almost as if you could see them grow. Lately, it seems to have slowed down a bit.
