Several years ago in Wyoming the perch would only take minnows that had been given a shot of scent. You could drop a minnow without scent in one hole and a scented one in a hole a foot away and the scented minnow would get bit immediately while the other just sat there all day. I don't recall the scent variety, but it was thick and stuck to the minnows. I made some out of glycerin and anise oil that seemed to work as well as the store variety. Also, from my relatives in Wisconsin, the crappie happy hour is the last hour up until dark. The plankton or mysids or whatever is living on the bottom start a rise to the surface which seems to trigger the crappie bite. They can see the water start to go cloudy and the crappie move in to feed.