Feed your betta once per day, and only as much as your betta will eat in a couple of minutes. This usually means a very small pinch of flakes, or two to three pellets. Pay attention to how much your betta is eating. If the food you are giving seems like too much, cut back. Choose a good-quality flake food or pellet as the staple of his diet. Better yet, find a few quality foods and alternate them so your betta gets a wider range of nutrition.
Overfeeding is one of the most common ways to make a betta fish ill. Uneaten food decays and fouls the water, and overfed bettas produce more waste. This means it is harder to keep the water clean. Too much food can also lead to physical problems for your fish. Avoid overfeeding, and you may be saving your betta from an early demise.