I'm overrun with freshwater Tadpole snails (Physa acuta). If you have puffers or the like these will be good as food. They breed like crazy. Pretty good at cleaning up algae though without stripping your plants. They are in my planted shrimp tank so I can't use snail killer or assassin snails (I've got other ornamental snails in there). I will post to UK for £1.50, 1st class Royal Mail in crushproof flat tub so parcel can fit through your door, as many snails as you like. I've got about 100 of them, about 0.5cm across.