I've seem some snail flies. They were so small though that I don't see how you could cast them without a ton of weight. You might be able to find snails in pet stores. I guess they use snails on the inside of glass fish tanks to keep the algae down. Don't know if you could get in trouble for this. Because if the snails could get away live and hurt the lakes natural ecosystem, you might not be able to use live ones. Just something to check into.