I've personally found that the leaches don't have much movement (like a nightcrawler) when on the hook. I've used crawdads with pretty good luck. There's a pond by the house (Beavertail Pond) that has billions of crawdad between 4" & 6", put a can of cheap cat food in a crawdad trap over nite, and you'll have a boat load of bait. Just make sure you get your hook as close to the tail as you can (without hookin the tail) in order to keep the bait on, and also so it can swim almost freely.
Good Luck & Tight Lines!!!
Pyro