I will have at least 20 bladder snails ready for re-homing at some point this week. They can be used for several purposes.
Food: It's good for some fish's diets to have a population of these guys going in a separate tank, and then every so often adding them as needed for food / a healthy balanced diet.
Bio film/ algae control: They also are great tank cleaners but you need to be mindful of baby snails clogging up your filter set-up. Do your research...