A good diet is a balanced one. I feed my Jardini, pellets and bloodworm every day. Then live food once or twice a week, and crickets or some other type of insect once a month. ( The insects are 90% protein )
If you have only 1 fish, heaps of filtration and water, and do regular water changes, you can feed the fish heaps and watch him grow QUICK. Just remember, when it comes to dead food ( pellets etc. ) only feed as much as they will eat in 3 minutes.