Eurasian minnow
A small shoaling cyprinid from cold running water, and one of the very few genuinely coldwater community fish. Males in breeding condition develop red and black colouring that most keepers never see because the fish is usually kept too warm to come into condition.
Quick profile
- Scientific name
- Phoxinus phoxinus
- Adult size
- 6–10 cm (2.4–3.9 in)
- Lifespan
- 3–6 years
- Temperature
- 2–20 °C (36–68 °F)
- pH
- 6.5–8
- Hardness
- 5–18 °dGH
- Minimum tank
- 90 L (24 US gal)
- Minimum length
- 100 cm
- Swimming zone
- All levels
- Social
- Schooling — at least 8
- Diet
- Micropredator
- Overall confidence
- moderate confidence
What keeping this species involves
Needs cold, fast, highly oxygenated water all year and a real winter to breed. Everything difficult about it is a temperature and oxygen question.
Cool, clear, well-oxygenated streams and the stony margins of lakes, in fast water over gravel.
Identity and names
- Common name
- Eurasian minnow
- Scientific name
- Phoxinus phoxinus
- Family
- Cyprinidae
- Order
- Cypriniformes
- Class
- Actinopterygii
- Also sold as
- common minnow, Phoxinus phoxinus, European minnow
Adult size and growth
6–10 cm (2.4–3.9 in)
Typical lifespan in an aquarium: 3–6 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: fusiform — the ordinary torpedo with a small terminal mouth. Assigned from what is typical of Cyprinidae, not examined for this species.
Water and tank requirements
A shoal of an active current-loving fish needs a run to use. The volume matters less than the length and the flow.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
Why these ranges: A cold, fast, oxygen-saturated stream fish. The band's upper end is a limit rather than a target — above about 20 °C oxygen falls and this species is among the first things in a European stream to be affected by it.
Where these figures come from
Habitat class
Hill stream and rapids
Fast, cool, oxygen-saturated running water over rock and gravel, typically at altitude or on a steep gradient.
Oxygen and flow are the requirement, not the chemistry. A hill-stream species in still water at the right pH is being kept badly, and the failure is slow enough that the keeper usually blames something else.
- Conductivity
- 50–300 µS/cm
- Flow
- high
- Dissolved oxygen
- near saturation
- Seasonality
- moderate
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.
- TemperatureReasoned on this record
- This record states its own reason for this band. See the water section.
- pHReasoned on this record
- This record states its own reason for this band. See the water section.
- General hardnessReasoned on this record
- This record states its own reason for this band. See the water section.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 2–20 °C (36–68 °F) | Stability matters more than hitting an exact figure. |
| pH | 6.5–8 | A stable pH outside the ideal band is usually better than an unstable one inside it. |
| General hardness | 5–18 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 90 L (24 US gal) | A floor, not a recommendation. |
| Minimum footprint | 100 cm long | A shoal of an active current-loving fish needs a run to use. The volume matters less than the length and the flow. |
| Water flow | high | Match the outflow to this rather than to the filter's rating. |
| Lid required | Yes | This species jumps. |
| Structure | Gravel and cobble, strong flow, and no still corners. |
Behaviour
- Holds station in current and feeds on drift, which is what the flow requirement is for.
- Jumps, particularly when startled in a shallow tank.
Telling males from females
Breeding males show red bellies, dark flanks and white tubercles on the head. Outside the season both sexes are olive and unremarkable.
Feeding
- Diet type
- Micropredator
- Staples
- Frozen daphnia and cyclops, Bloodworm, Small live foods, Sinking granules
Breeding
- Strategy
- Scatters eggs over gravel in fast water during a spring rise
- Difficulty
- challenging
- Parental care
- none
Needs a genuine winter and a spring temperature rise. Almost never bred in a tank that runs at one temperature.
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 | moderate | Cover reduces losses but rarely prevents them where the risk is high. |
| Shrimplets | high | 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. |
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.
- Sold and kept as a coldwater fish and routinely put in unfiltered, unaerated tanks. It needs more oxygen than a goldfish, not less.
- Wild-collected in many places, and subject to freshwater fishing law where it is native.
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
- Across Europe and northern Asia, from Britain and Ireland east to the Amur basin
- Habitat
- Cool, clear, well-oxygenated streams and the stony margins of lakes, in fast water over gravel.
Legal status and responsible practice
Where this species has been introduced, and what followed
Europe — recorded as introduced in 36 countries, first in Norway around 1900
EstablishedLive bait. A native European cyprinid that anglers have moved across the continent in bait buckets for over a century, and which is consequently listed as an alien in three dozen European countries.
- Bait-bucket release by anglersAn angler empties an unused bait bucket at the end of a session. Documented as the primary route for several crayfish and small fish, and almost entirely absent from the aquarium hobby's account of the problem.
What has been established
- Competition with native speciesReported in the literatureEASIN records an impact without scoring a sector. The concern in the Norwegian literature is competition with juvenile brown trout in oligotrophic lakes, which is a specific case rather than a general one.
A European native, sold occasionally for coldwater tanks, and a documented alien across most of Europe. It belongs with the noble crayfish and the three-spined stickleback as evidence that the label describes a border.
EASIN — European Alien Species Information Network · EASIN catalogue record R11382 (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 | Phoxinus phoxinus | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Across Europe and northern Asia, from Britain and Ireland east to the Amur basin | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 6–10 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 3–6 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 2–20 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 6.5–8 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 5–18 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 90 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 100 cm | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum group size | ≥ 8 | 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 2026-08-30. 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 checkableLimited evidence — treat with caution.
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. No checklist distribution statement is held for this species. The range on the page is editorial until one is.
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.
minimum group sizeAquariumHQ'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: group size — 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: 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.
- Schooling and shoalingThis species is recorded as school, and the number it is kept in decides how it behaves.
- Wild conditions and aquarium recommendationsThe water band on this page is an AquariumHQ position with a stated reason, not a measurement of a river.
- 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
A genuine schooling fish that becomes skittish and colourless in small numbers. Ten or more is where the behaviour appears.