It really depends on the size, age, and health state of your betta, as well as the size of your tank and the strength of your filtration. My fish are all athletes from living in large tanks with a reasonably strong current. They do fine with power filters, but because they need energy to fuel all the muscle mass they have from swimming in those conditions even with their big fins, they eat a *lot* of food. I feed twice a day anywhere from 4-6 pellets per feeding, and none of them are fat. In fact, I'm trying to "bulk up" Lug because he got sick and didn't eat for 3 days, and in that time dropped a ton of weight. I only fast maybe once a week, and a lot of times instead of fasting, I'll add maybe only 2 pellets per feeding. I will also try a high protien food like live blood worms at least once a week to keep them in good condition. However, if you have a betta in a 1 quart bowl with no filter who sits around on the gravel all day, he may only need 3-6 pellets a day rather than per feeding.