I tried the garlic! I cut up part of a glove into small bits and swished the other food in it with a little water too, to flavor it.
He ignored it at first, then took a nip -- then turned up his nose.
Then I saw him eat something very hard to see, I think it might've been a worm, probably growing in the tank from all the overfeeding I've been doing in general to try to get him interested in something. I recall having a problem with that way back, and that this was likely the reason.
I really don't want a tank full of worms from overfeeding, for him to eat. So I don't know whether this is good or bad. At least I think I saw him eat something very small.
I think this Betta is going to refuse all but live food.
I am wondering what to do. I wish I knew somebody who fed his fish live food and wanted a Betta.