I don't fast my betta's, They get fed everyday, once or twice, a blend of foods I pre-mix..
I don't feed frozen bloodworms very often at all, But when I do they get a squeeze full, guessing around a dozen worms or so,..
I wish I could help people who run into so many problems (sickness) with their fish, But fact is I very very rarely ever have any troubles even with all the amounts I keep. Prevention is far better then having to waste time on finding cures... I will stress one thing,, MANY many problems can be cured simple with good clean water, Frequent water changes,(several times a week) tank size and alot of observation, catch a thing before it becomes a problem, learning to read the little signs and you'll be ahead of the game. and another very big missed by many problem I've seen, A good Parasite med schedule.. Parasites alone can cause so many different problem, including many unexplained deaths.