You don't think the reason he won't eat could have something to do with you just caught him from the wild, transported him in some sort of tiny container that was exposed to all sorts of unnatural noises and plopped him in to a fish tank where nothing is familiar and some huge monster (you) keeps sticking its face in his?
This fish has never had so much light around it, never had the view of a person in its face, never had the view of a HOME, has never heard a radio/TV until now. He ate live bugs and fish in his old home, and you are trying to feed it what? He has always had the ability to swim a long ways from anything that was threatening or scary before, but now that doesn't work.
It came from water temp and pH of X and you have put it in a tank with a water temp and pH of Y.
Ohh and it also has an infection from the injuries it received as it was violently yanked from the water by its lips.
Yeah I would wonder why its not eating too.