How to Get Rid of Pest Snails in an Aquarium Without Chemicals

Cut the food first

Aquarium Co-Op, an aquarium retailer, says snails “can only create new babies if they have enough sustenance”. Aqueon, an aquarium equipment and food maker, says to feed only what fish “can consume in 2 minutes or less, once or twice daily” and to “Remove any food that remains after 5 minutes with a siphon or fine mesh fish net.” It adds: “Overfeeding is not a matter of how many times you feed each day, but rather the amount of food per feeding.” Our tropical fish food roundup compares foods.

Unplug the filter and heater, and wait if your heater’s maker says to

Fluval, a filter maker, says in its AquaClear manual: “CAUTION – Always unplug or disconnect all appliances in the aquarium from electricity supply before placing hands in water, before putting on or taking off parts and while the equipment is being installed, maintained or handled.” Hydor, a heater maker, says to unplug its heater “at least 30 minutes before any waterchange”, so before step 5. Follow your own equipment’s manuals.

Pick off the snails you can see

, by hand or with tweezers, with everything still unplugged (step 2). Co-Op says this “may not work as well” for Malaysian trumpet snails, which are “nocturnal and like to burrow in the substrate”.

Scrape off egg clutches

, still unplugged. Aquarium Breeder, a shrimp-keeping hobby blog, says eggs on glass “can easily be scraped or scooped out before they hatch. Use a razor blade for glass.” Co-Op, on algae: “Try using a razor blade (for glass tanks) or gift card (for acrylic tanks) to remove the algae from aquarium walls.” A blade is sharp (our caution); our algae scraper roundup sorts tools by glass and acrylic. Interpet: “Regularly turn over objects such as wood, and (once removed from the aquarium) use boiling water to kill attached eggs”. Boiling water scalds, so handle it with care (our caution).

Vacuum the substrate, still unplugged

Co-Op suggests gravel-vacuuming mulm, and notes that “If the snails are small enough”, some people siphon them into a bucket during water changes. It also says to prune plants and scrub off algae; our guide to getting rid of algae in a fish tank covers that clean.

Refill with treated water at tank temperature, still unplugged

Aqueon: “Always treat tap water with a water conditioner to neutralize chlorine and ammonia before adding it to the aquarium.” and “Replacement water should be the same temperature as the aquarium water.”

Plug the filter and heater back in

Aqueon’s cleaning checklist: “Plug the filter and heater back in.” Hydor says its heater “can ONLY then be turned back on when the Aquarium is full and the heater is completely submerged.” Fluval’s manual: “Do not allow filter pump to run dry.”

Bait a trap overnight

Co-Op, which sells the Easy Snail Collector, says to put food in its chamber and “wait overnight”, then lift it out; setting it flat with the substrate “makes it easier to collect Malaysian trumpet snails”. Its caution: “Some fish like bristlenose plecos may go in to use it as a cave. Make sure to check on the collector daily.” Without a trap, Buce Plant, a plant retailer, suggests romaine lettuce traps, then “simply lift the lettuce right out of the tank once they have gathered”. Unplug the filter and heater before your hands go in to set the trap or lettuce, and plug them back in (step 7) once it is set. Unplug again before you lift it out in the morning, then plug them back in.

Add a snail eater only if it suits the tank

Co-Op names almost all freshwater pufferfish, several loaches (clown, zebra, yoyo, dwarf chain) and the assassin snail. Buce Plant ties the choice to “the size of the tank and its inhabitants”. Aquarium Breeder: “Be careful—some snail-eating fish may also eat shrimp.” Aquatic Arts, which sells assassin snails: “There is a slight risk of an assassin snail eating a dwarf shrimp from time to time. They would much prefer to eat snails, but if given the opportunity there is a chance they could get a shrimp.” The sources differ on larger snails. Co-Op says assassins take snails “even those that are much larger in size”. Aquatic Arts says they eat snails “that are their size or smaller, but they will not harm snails that are larger (such as Mystery Snails, Giant Sulawesi Snails, and larger Nerite Snails)”, but also that “large groups of Assassin Snails have been known to gang up on a larger snail and take it down, so caution should be exercised when keeping these, even with larger snails.” Interpet: “It’s best to discuss this with your aquatic retailer before splashing out on new additions to your aquarium.”

Dispose of removed snails; never release them

Co-Op suggests feeding them to snail-eating fish, giving them to hobbyists who keep snail eaters, or crushing them “for a quick death”. Illinois-Indiana Sea Grant, a university research and outreach program, says: “Never release aquatic plants or animals into waterways!” For animals it says to ask a veterinarian or pet retailer about humane disposal; for debris and unwanted plants, a “sealed plastic bag in the trash. If possible, freeze the bag before disposal.”

Repeat, and test the water

Co-Op says eggs “can take 1-4 weeks to hatch, depending on the species and water temperature”, and Interpet advises: “Try a combination of methods from the list”. Interpet also warns: “Decaying snails can also create water quality issues which will affect the health of your fish.” Test ammonia and nitrite; Practical Fishkeeping, a fishkeeping magazine, says “A mature tank should have zero readings for ammonia and nitrite”. Above zero, see our guide to what causes ammonia in a fish tank; keep testing until both read zero.