We do all we can to prevent these unwanted guests from traveling with our plants, but snails and sometimes other critters are tricky and can slip through the cracks. We treat our plant tanks with Fenbendazole, an anti-parasitic medication that kills snails and worms but does not harm most other aquatic animals or plants. Unfortunately, this does not work 100% of the time. It is very common for plant sellers to unknowingly send snails with plants, because pest snails are pros at hiding their eggs inside the plants.
We have found that the best and safest solution to a snail infestation is to add assassin snails to your tank. We sell the snails in groups of one, three, five, and twelve snails. There are also many other sellers and stores online that offer assassin snails. If your snail infestation is particularly bad, the general rule is that you need about five assassin snails per ten gallons.
If you have snails in your tank that you do not want harmed by assassin snails, there is another trick that can help take care of pest snail overpopulation. We call it the “lettuce trick.” First, lightly blanch a leaf or two of lettuce for about ten to twenty seconds. Then place the lettuce in your tank and turn off the lights for a few hours, or overnight. Once you turn your lights back on, you should find that the lettuce is covered in pest snails. Simply remove the lettuce, along with all of the nuisance snails attached to it, and dispose of it. This method works best if you haven't fed your tank in a day or two, so the pest snails are good and hungry.