I think it's definitely better to eliminate snails through baiting and picking them off than to add fish to fix the problem. Adding fish increases bioload (not to meantion, clown loaches grow pretty large!), and that will just cause more problems in the tank. Chemicals kill the snails, but then you have a bunch of rotting snail corpses fouling water quality, unless you pick them all out. If you're going to do all that, you may as well pick them out alive.