I too feel NLS (new life spectrum) is the best, and it is fairly cheap. The Hikari is a good brand, staple is more vege based and does good with the more vegetarian cichlids, Bio-Gold is more for the meat eaters, and young fish because it has more protein. The Bio-Gold+ has bacteria in it to help metabolize waste, and aid in digestion, but also comes with a hefty price tag, $20 a bag, compared to $9 for regular Bio-Gold. Most fish aren't too picky and as long as they have a varied diet they will always show off good colors. To test and see which food would be the best, you would have to set up a control group of the same fish, and try each of the in question foods, and see what you get. I might even try it with some convicts........... 1 10gal for omega, 1 10 gal for staple, 1 10 gal for gold, 1 10 gal for NLS..........Anyone got 4 10 gal tanks and for male, or female convicts?????? Build a sump which gives them all the same water.