Tilapia have an odd reproductive approach. They can start breeding at 4 mths old and hatch a new batch about every 30 days. The most productive method is to move some but not all. I would keep my first breeders and move the offspring at 4-5 inches. Repeating through summer. In about Sept I would move all of the balance to the big pond. That should provide the max poundage from the grow out pond over spring and summer.