You could drop a stick in, but they'll quickly be consumed by the snails, often it can be just a matter of hours until the snails take care of the sticks, producing their high waste amounts in even higher quantity and that could cause a lot of trouble for the fish. So I agree with Dino - I'd feed them the day you leave & get back, doing a partial
water change and cleaning as close to the last feeding as your schedule allows.
On a side note, if you didn't add the snails intentionally, you may want to consider getting rid of them, they reproduce ridiculously.