hi, i am wondering what size minnow is too small for any kind of bait fishing. for instance, would a minnow of about half an inch be good bait for anything at all? i am mainly going into trout fishing. im mostly set up for smaller trouts at the moment.

A small trout will no doubt eat a tiny minnow, provided you can hook and keep it on a hook. It doesn't have to be alive, trout have no problem scavenging dead minnows.

The problem with a minnow that size is that the line, hook, and split shot tend to make it drift unnaturally because it is just such a small bait. Back in my elementary school days I was known to net mosquito fish for crappie bait, and did well with them, so it is possible.