TJ here is a bit from an upcoming Cutting Edge article

. In this study with young Bluegill six practical diets were formulated, with varying levels of protein (32–44%) and lipid (6–12%). Final weight during the test period, feed intake, and feed efficiency values increased with increasing levels of dietary protein. Increasing the lipid content by 4% in the 32%-protein diet (to 10% lipid) or the 44%-protein diet (to 12% lipid) had little influence on the performance of the fish. Although the fish grew well on all diets tested, they grew best when offered a diet containing 44% protein and 8% lipid. Other studies show that because fish growth often is limited by food availability, 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).