Bladder snail
The snail nobody buys and almost everybody ends up with, arriving on plants as eggs. It is treated as a pest and is mostly a symptom: a population that explodes is telling you the tank is being overfed, because the snails are eating what the fish did not.
Quick profile
- Scientific name
- Physella acuta
- Adult size
- 0.6–1.5 cm (0.2–0.6 in)
- Lifespan
- 1–2 years
- Temperature
- 10–30 °C (50–86 °F)
- pH
- 6–8.5
- Hardness
- 2–25 °dGH
- Minimum tank
- 10 L (3 US gal)
- Minimum length
- 20 cm
- Swimming zone
- All levels
- Social
- Tolerant of any grouping
- Diet
- Detritivore
- Overall confidence
- moderate confidence
What keeping this species involves
Survives conditions that kill almost everything else, including low oxygen and wide temperature swings. Nothing about it is difficult.
Almost any still or slow fresh water, including heavily polluted and degraded sites.
Identity and names
- Common name
- Bladder snail
- Scientific name
- Physella acuta
- Family
- Physidae
- Order
- Hygrophila
- Class
- Gastropoda
- Also sold as
- pest snail, tadpole snail, acute bladder snail, Physella acuta, Physa acuta
- Former or synonymous names
- Physa acuta
Adult size and growth
0.6–1.5 cm (0.2–0.6 in)
Typical lifespan in an aquarium: 1–2 years. Almost every animal sold in a shop is a juvenile, so the tank has to suit the size in the first line rather than the size in the bag.
Shape, which is what the compatibility engine reads instead of length alone: globose with a grazing or sucking mouth. Assigned from what is typical of Physidae, not examined for this species.
Water and tank requirements
Not a species anybody sets a tank up for. The figures record the minimum in which a population can be maintained deliberately, which some keepers do as live food.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
Where these figures come from
Habitat class
Temperate still water
Ponds, lakes, canals and slow rivers outside the tropics, with a genuine winter.
The temperature range is the point. These animals experience a seasonal cycle, and keeping them at a constant tropical temperature shortens their lives without ever looking like the cause.
- Conductivity
- 150–800 µS/cm
- Flow
- still
- Dissolved oxygen
- variable
- Seasonality
- strong
These are figures for the KIND of water body, not measurements of this species. They are AquariumHQ’s summary of the general limnology and are given wide because the water is.
- TemperatureFollows the habitat this animal comes from
- Follows the water this animal is recorded from — temperate still water. Temperate still water generally runs 2–28°C, and the advised band of 10–30°C is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species.
- pHFollows the habitat this animal comes from
- Follows the water this animal is recorded from — temperate still water. Temperate still water generally runs 6.5–8.2, and the advised band of 6–8.5 is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species.
- General hardnessSet by a requirement of the animal
- Hardness here is a shell requirement, not a habitat statement. A snail or mussel builds and repairs aragonite continuously, and in water without dissolved calcium the shell erodes faster than the animal can replace it — visibly, at the apex first. The band is therefore set by what the animal has to take out of the water rather than by what its river happens to contain, and several of these species are recorded from water considerably softer than the band advises.
Scale: -2.2 to 34.2 °C.
Scale: 5.6 to 8.9 pH.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 10–30 °C (50–86 °F) | Stability matters more than hitting an exact figure. |
| pH | 6–8.5 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 2–25 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 10 L (3 US gal) | A floor, not a recommendation. |
| Minimum footprint | 20 cm long | Not a species anybody sets a tank up for. The figures record the minimum in which a population can be maintained deliberately, which some keepers do as live food. |
| Water flow | low | Match the outflow to this rather than to the filter's rating. |
| Lid required | Recommended | Reduces evaporation and prevents accidents. |
| Structure | Any surface with biofilm. It has no structural requirements worth stating. |
Behaviour
- Crawls the underside of the surface film as readily as the substrate.
- Numbers track available food closely, rising within days of overfeeding.
Feeding
Eats what is left over. It damages healthy plants far less than its reputation suggests, and works mostly on dying tissue.
- Diet type
- Detritivore
- Staples
- Detritus and uneaten food, Algae films, Decaying plant matter
Breeding
- Strategy
- Self-fertilising hermaphrodite laying gelatinous egg masses
- Difficulty
- incidental
- Parental care
- none
A single snail can populate a tank. This is why removing visible adults does not work as a control.
Tankmates and compatibility
Assessments are derived from stored traits by the compatibility engine, with the reasoning shown. A verdict is a statement about probability, not a guarantee — individual temperament can override it.
| Towards | Risk | What it means |
|---|---|---|
| Small fish | none | Anything that fits in the mouth is at risk once this species reaches adult size. |
| Adult dwarf shrimp | none | Cover reduces losses but rarely prevents them where the risk is high. |
| Shrimplets | none | Determines whether a shrimp colony can grow rather than merely persist. |
| Snails | none | Applies to snails you wanted as well as snails you did not. |
| Long or trailing fins | none | Fin damage is an entry point for secondary infection. |
| Plants | none | Tough species such as Anubias and Java fern survive most grazers. |
Assessed pairings
Any pair in the catalogue can be assessed with the compatibility checker.
Welfare considerations
Points where the way this species is commonly sold or kept differs from what it actually needs.
- Killed wholesale with copper-based snail treatments, which also kill shrimp and are a heavy-handed answer to a feeding problem.
- Its presence is a useful signal rather than a fault: a population that suddenly increases usually means food is going uneaten.
Problems to watch for
Most problems in a tank containing this species are general rather than species-specific. Start with the troubleshooting index and work from the observation rather than from a guess at the cause.
What AquariumHQ does not yet hold
Species-level disease susceptibility is modelled in the graph and is not yet populated. Health pages will not be published until each condition has veterinary sourcing, because health content written without evidence is the most harmful thing this product could publish. The gap is recorded in the coverage report.
Where it comes from
- Native range
- Originally North America; now established on every continent except Antarctica through the aquarium and plant trade
- Habitat
- Almost any still or slow fresh water, including heavily polluted and degraded sites.
What the checklists say
101 distribution statements retrieved from GBIF checklists. Establishment means is reproduced from the source where it states one, and left unstated where it does not — a record of presence is not a record of origin.
| Status | Places | What this means |
|---|---|---|
| Introduced | 54 | A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal. |
| Recorded as present, establishment means not stated | 47 | The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in. |
No checklist AquariumHQ holds positively calls this species native anywhere, so the native range above rests on AquariumHQ’s own reading of the literature rather than on a cited checklist.
Legal status and responsible practice
Restriction note
Established worldwide through the plant and aquarium trade and regarded as invasive in many regions. Its arrival is almost always accidental, so it is rarely the subject of a keeping restriction — but some jurisdictions do list nuisance aquatic snails, and AquariumHQ has not checked the position anywhere specific. Check locally before deliberately moving or selling them, and never release aquarium water, plants or substrate into natural water or drains.
Where this species has been introduced, and what followed
Europe — recorded in 40 countries, first in Austria around 1800
EstablishedPresent in forty European countries, which is more than any other species in this batch, and recorded from around 1800. EASIN lists biological control and other intentional release alongside the aquarium and ornamental routes. The biological-control entry is hard to credit for a species of this kind and is recorded as EASIN gives it rather than quietly dropped.
- Deliberate aquarium releaseSomebody took the animal out of a tank and put it into open water. The commonest reason is that the fish outgrew the aquarium, which is why size at maturity is a conservation question as well as a welfare one.
- Deliberate stockingSomebody put the species into open water on purpose, for food, angling, ornament or mosquito control — frequently a government agency, and frequently before anyone considered the consequences.
- Arrived with a shipment of something elseThe organism was not the thing being shipped. Snails on aquarium plants, clams in shellfish consignments, apple snails in farmed crayfish.
What has been established
Nothing. The species is present outside its native range and no study has measured what it does there. The absence of data is not the absence of effect — it means the question has not been asked, and this is the ordinary state of the evidence for most aquarium species that have established somewhere warm.
EASIN — European Alien Species Information Network · EASIN catalogue record R11467 (apixg/catxg) · read 2026-08-30. A European network: the routes and effects recorded here are the ones documented in Europe. EASIN compiles national inventories, DAISIE and CABI rather than measuring, and its pathway assignments carry its own uncertainty flags, which are reported above where it sets them.
Never release aquarium life into the wild
Aquarium animals, plants, and aquarium water must never be released into ponds, rivers, canals, drains or the sea — not even in a country where the species is sold freely. Released fish and invertebrates establish populations that displace native species, and released plants and water carry pathogens, parasites and fragments capable of spreading without any animal at all. If you can no longer keep an animal, rehome it through an aquarium society, a retailer that accepts returns, or another keeper.
- Rehome through a local aquarium society, a specialist retailer or another keeper.
- Unwanted plants go in household waste or a hot compost heap, never in a watercourse or a garden pond.
- Never empty a bucket of tank water into a drain that discharges to open water.
- If an animal is beyond rehoming, ask an aquatic veterinarian about humane euthanasia rather than releasing it.
Legal status is recorded from the sources named and was correct on the verification date shown. Rules change, and sub-national rules often differ from national ones. Check the current position with the relevant authority before acquiring, selling or moving any animal or plant.
Evidence
Every stored value with the kind of support behind it and where to check it. Evidence type and confidence are separate axes: an editorial position held confidently and a measurement held tentatively are different things.
| Claim | Value | Evidence type | Confidence | Source |
|---|---|---|---|---|
| scientific name | Physella acuta | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Originally North America; now established on every continent except Antarctica through the aquarium and plant trade | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 0.6–1.5 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 1–2 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 10–30 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 6–8.5 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 2–25 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 10 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 20 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
Last reviewed 2026-08-10. Values labelled as an aquarium-literature consensus are AquariumHQ editorial positions rather than measurements — see how evidence is handled.
Why we say this
What each figure on this page rests on, and how far that is from being independently established.
Every figure on this page has a provenance. Open any claim to see what AquariumHQ holds for it, which sources say what, and what a claim of that kind actually needs. Different claims need different evidence: an accepted scientific name is settled by one authority, while a legal restriction needs a current primary instrument. A single source is often the right answer rather than a thin one.
scientific nameAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: accepted scientific name and classification — 1 authoritative source in an appropriate context. Checked against gbif on 2026-08-12. One authoritative backbone is what this class requires.
What would improve this: Go and read a source. This is reachable and has not been reached.
native rangeAquariumHQ's own position, externally checkableBased on a verified authoritative source.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: where the species occurs — 1 authoritative source in an appropriate context. 101 distribution statements held from GBIF checklists — introduced in 50 country. Establishment means is reproduced from the source, never inferred from occurrence.
What would improve this: Go and read a source. This is reachable and has not been reached.
adult sizeAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
lifespanAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
temperatureAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
phAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
general hardnessAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.
AquariumHQ's own position on a claim an external source could support.
What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.
What would improve this: Go and read a source. This is reachable and has not been reached.
minimum tank volumeAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
minimum tank lengthAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.
No external authority publishes this. The rationale carries the reasoning.
What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.
What would improve this: Keep the rationale current. There is no source to find.
Guides relevant to this species
Chosen from this record's own traits rather than listed on every page.
- Native, introduced and invasiveThis record carries an invasive or legal note, and those are five separate claims that are easy to read as one.
- Scientific and trade namesThis species has been published under more than one accepted name.
- The kinds of water aquarium fish come fromThis record's water bands follow temperate still water, which is the kind of water this animal is recorded from.
- How aquarium species get into the wildThis species has a documented introduction outside its native range, with the route recorded.
Group size and social behaviour
Hermaphroditic and self-fertile: one individual is enough to found a population.