Got 3 adf's how often do i need to feed them

there in with like 5 little goldfish, 2 cory catfish and 1 chinese algae eater
have been feeding them blood worms by hand but i notice the fish eat this also any suggestions on options to feed them that i can buy in bigger amounts aka less trips to pet store. If goldfish need to go they can (ill just feed them to my african bull frogs)

Thanks for the input