put anywhere from 1/4 to 1 tsp per gallon of water and do twice weekly water changes. Feed him 1 pellet every couple hours throughout the day up to 8 total pellets daily so his body has plenty of nutrients to rebuild his fin and he should be fine in no time. My betta split his fin one day and I was in panic mode but noticed his fin was healing almost immediately it took a week to heal, some people were saying months to heal.