I do use them a lot for bait. I mostly use them when fishing for smallmouth bass in a river near where I live. It seems that the best time to get them is soon after they have molted, when they are considered soft-shelled. I often take their pinchers off unless they are small. I rig them by using no more than a 1/0 hook, hooking them from the bottom of the tail up through the top. I put a split shot about 1 foot up the line. What is bad about using crayfish is that they will craw into crevaces and get you into a lot of snags. To help avoid this problem, I only let them walk around on the bottom for a minute or so before jigging them off the bottom once. This also helps get fishes attention. I have also had luck with catching channel cats in a local lake using crayfish on a gravel bottom. Good luck!