I should clarify, I had no predators in my pond when I used them and I stocked about 20 pounds of fish mostly in the 4-5" range and a few 6" ones. They grew nicely that summer but I can't say a fingerling would have had time to grow to adult size.

if you want to experiment with feeding them pellets and seeing how they grow you would want to put a tank or blocking net in your pond to protect them from predation and see how they actually do. The other advantage of this approach is it would be easy to get them back out if you desire when water is cold and have a fish fry!