Snail numbers follow the food supply, so cut the feeding, remove snails by hand and with a lettuce trap, and vacuum the gravel weekly. Copper snail treatments are toxic to invertebrates, and the assassin snail cannot legally be imported or traded in Australia.
Here’s how to get rid of snails in a fish tank. Feed less, because leftover food and waste are what snails breed on. Then pick out the ones you can see, trap the rest with blanched lettuce overnight, and vacuum the gravel each week. Skip the copper treatments and the assassin snail: one harms everything else in the tank, and the other is illegal in Australia.
Scope: this guide is for pest snails (small bladder, ramshorn and trumpet snails) in a freshwater fish tank. A shrimp tank or a heavily planted tank changes which treatments are safe. Snails you bought on purpose are a different matter, covered in the snails and pests guides and the best snails for aquariums roundup.
Why You Have Snails in Your Fish Tank
Pest snails almost always arrive as tiny eggs or juveniles on new plants, decor or a bag of water. A single one can start a colony, because many pest species can breed without a partner. Numbers then climb with the food available, so a sudden boom points to too much food or too much waste in the tank.
They are rarely harmful in small numbers. A few snails eat algae and leftovers. The trouble starts when hundreds crowd the glass, clog the filter intake and signal that the tank has more waste than it can process.
How to Get Rid of Snails in a Fish Tank: 5 Steps
- Cut the food supply. Feed only what the fish finish in a couple of minutes, and scoop out the rest. Snails breed on uneaten food and on the waste it becomes, so this is the step that actually lowers the population.
- Pick them out by hand. Remove every snail you can see, once a day for the first week, using tongs or a small net. Check the plant leaves, the decor and the underside of the lid.
- Set a lettuce trap. Blanch a lettuce leaf or a slice of cucumber, weigh it down on the substrate at night and lift it out the next morning with the snails on it. Repeat for a week or two. The blanching softens it, so snails come to it at night.
- Vacuum the gravel weekly. A gravel vacuum removes waste and snail eggs at the same time. Combine it with your normal water change, and use treated water for the refill.
- Inspect new plants and decor. Check each new plant and rinse it in a bucket before it goes in. Look for the clear jelly clumps of eggs on the leaf undersides and pick them off, which stops the next round.
Expect the population to fall over several weeks, not overnight. If you are still finding dozens, go back to step one and cut the food further.
New plants are the usual source, so it pays to know what you are buying. The what plants can I put in my fish tank guide covers how to check and plant them.
What Not to Use to Get Rid of Snails
Assassin snails are the fix many overseas guides suggest, but they are not legal in Australia. Business Queensland says assassin snails cannot be legally imported or traded in Australia under the Environment Protection and Biodiversity Conservation Act 1999, and that you must not sell or trade them on any marketplace. Research in Marine and Freshwater Research warns they are a major risk to Australian freshwater environments, because no native freshwater snails in Australia are carnivorous. If you find some for sale online, don’t buy them.
Copper-based snail treatments are the other trap. A UF/IFAS publication states that copper is toxic to invertebrates such as snails, so it also kills shrimp and other snails you may want to keep, and its toxicity to fish rises as alkalinity falls. Copper is also hard to get out of a tank afterwards. Avoid it unless the tank holds only fish and you have nothing else in it.
Some fish eat snails, but adding a snail-eating fish is a stocking decision that affects the whole community. Check size, temperament and your state’s rules for the species first, because keeping some fish is restricted in parts of Australia and the rules differ by state.
How to Get Rid of Snails in a Fish Tank for Good
- Feed lightly and clear leftovers, since food is what the snails live on.
- Keep to your cleaning routine. See how often to clean a fish tank and how to clean a fish tank for the schedule.
- Quarantine new plants in a bucket of treated water for a few days, and inspect them before they go in.
- Consider a few nerite snails if you want a clean-up crew. They can’t breed in freshwater, which the best snails guide explains.
Common Mistakes
- Tipping snails into a creek, pond or drain. Introduced snails can spread and harm native species, so bag them and put them in the bin.
- Dosing a snail killer with plants or shrimp in the tank. The copper will kill the invertebrates and can stress fish.
- Removing the snails but not cutting the food. The population will bounce back within weeks.
- Ignoring the eggs. Clear jelly clumps on leaves and glass hatch into the next wave.
When to Call It
If snails are still exploding after 4 weeks of light feeding and daily removal, test the water, because a large snail population can point to high nitrate or ammonia. Use the test guide and fix the underlying waste first. Persistent problems in a planted tank sometimes mean stripping and rinsing the plants, then replanting them, which is a job to do in one go.
Related Guides
Keep reading on the same topic:
Frequently Asked Questions
How do I get rid of baby snails in a fish tank?
Reduce feeding, vacuum the gravel and pick off the eggs and juveniles you can find. Baby snails grow up fast when food is plentiful, so the food supply is the lever that works.
Do snails harm fish?
Not directly. Pest snails eat algae and leftover food and don’t attack healthy fish. A big population mostly signals excess waste and can clog filter intakes.
Will snails go away on their own?
Only if the food supply drops. If you cut feeding and clean regularly, numbers fall. If you don’t, they tend to keep growing.
Can I use an assassin snail in Australia?
No. Assassin snails are prohibited from import and trade in Australia. Don’t buy them online, and if you already have some, contact your state biosecurity department.
Is it safe to use copper snail treatments in a fish tank?
Not with invertebrates, and with care even for fish. Copper is toxic to snails and other invertebrates and is harder on fish in soft water.
