I don't know how to be sure. What happens over several generations of GSF back breeding? I recently caught a mutt. It was about 10.5 inches and the body looked like pure BG. But, it had the green spots along the jaw area and the larger mouth. It was a magnificent fish that I immediately returned to the water. I have no idea what % GSF it was.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP