Most store bought flakes are good for daily nutrition.  You can supplement the diet by adding brine shrimp, blood worms or seaweed flakes, depending on your fish.  Fish also enjoy slices of cucumber, wish should be taken out at the end of each day.

Many fish owners feed their fish twice a day.  Watch your fish eat so you can see if any look sick or disinterested in food.  If there is food left after ten minutes, you have put too much in the tank and should put less in next time.