How to Get Rid of Snails in a Fish Tank
A few snails do no harm. Hundreds of them on the glass usually mean there is too much food in the tank. Fix that first and the rest gets much easier.
Feed less, clean up leftovers, and put a piece of blanched vegetable in the tank at night. Lift it out in the morning with the snails on it. Repeat for two or three weeks and scrape off any egg clusters you see.
Where they came from
Almost always from new plants. Snail eggs sit on leaves as tiny jelly blobs and are easy to miss. They can also arrive on driftwood or in the water from the shop.
Which snails do you have?
- Bladder or pond snails: small, with a thin rounded shell. These multiply fastest.
- Ramshorn snails: a flat, coiled shell like a tiny rams horn.
- Malaysian trumpet snails: a long pointed cone. They spend the day in the gravel and come out at night, and they do turn the substrate over, which is useful.
None of these usually harm healthy fish or plants. They eat leftovers, algae and dead leaves. The real issue is numbers, and the way they look.
How to clear them
- Cut the food. Give only what your fish finish in about two minutes. Snail numbers follow the food supply.
- Clean up. Vacuum the gravel at your next water change and trim dead leaves.
- Bait them. After lights out, place a piece of blanched cucumber or zucchini on a small plate or in a trap on the bottom. In the morning, lift it out with the snails on it. How to blanch vegetables.
- Remove eggs. Scrape jelly-like clusters off the glass and leaves with an old card or scraper.
- Keep going. Do this several nights a week for two or three weeks. Eggs keep hatching, so one night will not finish the job.
What about snail-eating fish?
Assassin snails work slowly and stay small, which suits many tanks. Loaches also eat snails, but some grow large and need a big tank, so check the adult size first. Never buy a fish only to solve a snail problem if your tank cannot suit it for life.
Why not use a snail killer?
Many snail treatments are copper based. Copper kills shrimp as well, can stress some fish, and can stay in the tank long after you stop. If a treatment works too well, a lot of dead snails rotting at once can also cause an ammonia spike. Keep chemicals as a last resort, and never use them in a shrimp tank.
Stop them coming back
- Keep new plants in a separate tub for two to three weeks and check them for eggs.
- Do not pour shop water into your tank.
- Keep feeding light.
- Never release unwanted snails into drains, lakes or rivers.