Here in KY, most lakes have a size limit on Crappie, with a few having no size limit ... but, using them as bait is illegal. But, even if legal to do, it would be easier and more "constructive" (in a conservation way) to just catch a Green Sunfish and use meat strips from it. No "bream" species are considered "sport fish" except the Shellcracker (Redear Sunfish) ... but, even they can be used as bait if less than 6" long. All the others (Bluegill, Longear, Pumpkinseed, etc) are legal to use for bait at any size.

I mentioned Green Sunfish because they're so easy to catch. All I have to do is cast a 1/16oz marabou Road Runner within a foot or two of the shoreline of a rocky bank, and chances are I'll have one on ... sometimes before I can even close the bail or start to make a turn of the reel handle !!