About the only fresh water fish I filet is bass (usually small mouth) and that is because of the method used for cooking. Now, as for gills, any ole fisherman worth his salt KNOWS fish taste better cooked with their heads on. About the only way you will prove this to yourself is the taste test. Cook one each, with head on and another without, in the same pan, corn mealed or floured the same way, and have at it. By the way, a fileted gill (IMO), not even in the same league.