If you get assassin snails, let them do their job. Wait a couple weeks after you see the last snail then sell them or something. I still have my assassin snails, and I do not mind them. When the snails are gone they eat those little pieces of broken rock that are in every tank with a rocky bottom. I am keeping them in other tanks on standby. All my new plants go into their tank for a few days before I add them to my main tank. Freshwater puffers eat snails, but they are highly aggressive.