There is a lot to this as the thread suggests. Keep in mind its energy in = energy used + growth and - loss. Its not just energy in = growth. For example natural food is better nutritionally but there is an energy cost to catch it. Pellets are easy to catch with little energy cost to acquire. Here is one point from a study that will be in PB soon " supplemental feeding is a logical tool to improve the condition of fish in small impoundments as the energy cost for bluegill to feed on pellets is small relative to the high caloric intake, which can be 4-5 times greater than those fed natural foods (Schalles and Wissing 1976)." Contrast that to the info above about how much in pellets it takes to match the nutrition of live prey.