Liveaquaria says "
Though peaceful, keep in mind that the Bumble Bee Snail is a carnivore. If there is insufficient food, the Bumble Bee Snail may feed on other snails in your aquarium or indiscriminately consume polychaetes whether beneficial or the more troublesome bristleworm. In well-established systems, most Bumble Bee Snails do not require supplemental feeding. However, if sufficient food sources are unavailable, supplement their diet with offerings of meaty foods, including finely chopped brine or mysis shrimp and frozen meaty foods. "