West Virginia State did a similar study and got similar results.
http://aquaculture.davis.wvu.edu/r/download/28443
They tested feeds with protein 35-46% and fat 3-18%. They conclude the best growth came from 44.5protein & 18% fat feed.
My regression analysis again says protein is not a driver (essentially zero influence, but still negative) and fat is the key.

Per other literature from profs in Iowa and Mo, bluegill want 36% protein during grow-out phase. That's the low range among fish feeds.
http://extension.missouri.edu/p/G9473
http://www.agmrc.org/commodities__products/aquaculture/bluegill-and-sunfish/

Talk centers on protein needs of bluegill, but nobody seems to discuss the data saying fat requirements are more important.