Adult betta fish only need to be fed once a day, whereas young betta fry should be fed twice a day. In addition, most professionals also recommend allowing betta fish to skip meals once in a while to give their digestive system a break and to allow for their body to get rid of any toxins that may have accumulated in the meantime.
Feed betta fish only as much as they can consume within 2 minutes. Avoid providing them with too much food, as it will only sink to the bottom of the tank and rot. This will cause the tank to become polluted.