I leave them alone. I have these snails and the tiny ramshorns in my tanks. Well, I do suck out the ones on the walls of the tank during a water change, but that's all.
Snails in a tank are not a bad thing, they are part of the ecosystem. The way to stop them getting out of control is to not over feed the fish.
Ok thanks a lot for your advice. I've left him in for now. Haven't seen him for a few days though. Not sure if he's in the live plants I have or whether someone has had a nibble at him. I guess we'll see. Thanks again.