These links are probably more than you want to know. There is another recent thread on the subject also. IMO a lot of pelleted foods would work fine for GS. I would use GFC because it has a little more of lipids/proteins needed by them than plain catfish food (see fact sheet below). I hesitate (although it is done by many acqaculturists) in using bulk organics ( cotton seed meal , soy meal etc) because they are not as complete a diet or as efficient and add bulk to the pond that can effect water quality.

http://srac.tamu.edu/tmppdfs/381285-121f...3fe87e31a608627

http://srac.tamu.edu/index.cfm?catid=2