The best way to feed a betta is a little at a time several times a day and to make it a variety. Try feeding Princess 2 pellets 3 times a day and fasting him one day a week. Better yet, feed 2 pellets twice a day and some frozen or freeze-dried bloodworms for the third meal (still fast one day a week). Only give a very tiny bit of the frozen or freeze-dried foods - most people on the forum seem to prefer giving the freeze-dried as a treat only once or twice a week. I usually give it once a day but I give only a piece of worm, not the whole thing. Usually less than half an inch long, more like a quarter inch.
I feed my guy Top Fin Color Enhancing Betta Bits, 39% protein. I think it's only available at Petsmart. New Life Spectrum's betta formula is very good, too. My Petco had it, maybe one in your area does too. If you can ever find it, Omega Betta Buffet Pellets are also a very good formula.