Bill, I have been working on sexing RES and as a general rule of thumb I wouldn't try to sex a RES under 5-1/2" in length, the results are just too iffy. With that said could they sexual mature at smaller size? My guess is yes they could and I wouldn't be surprised to see it happen in a newly stocked pond that lacks large mature male RES. We know that the presence of large male BG can suppress the sexual maturity of smaller male BG, I'm guessing RES follow a similar pattern. Age, size, and for the lack of a better term, "social structure", can play a role when sexual maturity starts.
