Actually, the 4 minnows (even the small ones) made fine work of about a dozen flies. I swear, these minnows are part piranha or something--they constantly nip at my tweezers and they are truly fearless.
Anyway, after I took a peek at the flies after an overnight "chill" in the fridge, I realized my "how do you feed them" question was a bit dumb--the cold sure does stun them. I was afraid I'd have trouble keeping them from flying away. I just dumped them in and the minnows did the rest.
Well, they seemed to enjoy the snack. If we couldn't enjoy the bread, at least the fish got something out of it.