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FishfreshwaterUndemandingHigh invasive risk

Guppy

Domestic guppies are hard-water fish, which is the opposite of what most people assume. They are also among the most widely introduced fish on Earth — released deliberately for mosquito control and now established across the tropics with documented harm to native species.

Quick profile

Scientific name
Poecilia reticulata
Adult size
3–6 cm (1.2–2.4 in)
Lifespan
1–3 years
Temperature
22–28 °C (72–82 °F)
pH
7–8.5
Hardness
8–25 °dGH
Minimum tank
60 L (16 US gal)
Minimum length
60 cm
Swimming zone
Upper level
Social
Loose group — at least 6
Diet
Omnivore
Overall confidence
high confidence

What keeping this species involves

Hardy in hard alkaline water. In soft acidic water — the conditions most guppy care sheets suggest — modern strains are prone to persistent bacterial problems.

Warm, hard, often mineral-rich streams, ditches and coastal drains.

Identity and names

Common name
Guppy
Scientific name
Poecilia reticulata
Family
Poeciliidae
Order
Cyprinodontiformes
Class
Actinopterygii
Also sold as
millionfish, fancy guppy

Adult size and growth

3–6 cm (1.2–2.4 in) — Males 3–3.5 cm; females 5–6 cm and considerably bulkier.

Typical lifespan in an aquarium: 1–3 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.

Water and tank requirements

A group of six or more with the sex ratio needed to protect females from constant pursuit.

RequirementValueNotes
Temperature22–28 °C (72–82 °F)Stability matters more than hitting an exact figure.
pH7–8.5A stable pH outside the ideal band is usually better than an unstable one inside it.
General hardness8–25 °dGHCheck your supplier's published figure before choosing species.
Minimum volume60 L (16 US gal)A floor, not a recommendation.
Minimum footprint60 cm longA group of six or more with the sex ratio needed to protect females from constant pursuit.
Water flowlowMatch the outflow to this rather than to the filter's rating.
Lid requiredRecommendedReduces evaporation and prevents accidents.

Group size and social behaviour

Not a schooling fish, but a social one that is subdued when kept alone.

Structure
Loose group
Minimum group
6
Sex ratio
Two or three females per male, or males only. A single female with several males is harassed continuously and it shortens her life.

Behaviour

  • Males pursue females almost continuously; the sex ratio is a welfare matter rather than a preference.
  • Fancy strains with large trailing tails swim poorly and are prime targets for fin-nippers.

Telling males from females

Males are small, colourful, with a modified anal fin (gonopodium). Females are larger and plainer.

Feeding

Diet type
Omnivore
Staples
Small dry foods, Frozen daphnia and brine shrimp, Blanched vegetable matter

Breeding

Strategy
Livebearing; females store sperm and produce successive broods
Difficulty
incidental
Parental care
bearer

A female bought from a shop is almost always already gravid and can produce several broods from one mating.

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.

Risk this species poses to common tankmates
TowardsRiskWhat it means
Small fishnoneAnything that fits in the mouth is at risk once this species reaches adult size.
Adult dwarf shrimpnoneCover reduces losses but rarely prevents them where the risk is high.
ShrimpletsmoderateDetermines whether a shrimp colony can grow rather than merely persist.
SnailsnoneApplies to snails you wanted as well as snails you did not.
Long or trailing finsnoneFin damage is an entry point for secondary infection.
PlantsnoneTough 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.

  • Heavily line-bred strains are less robust than feeder-grade or wild-type stock.
  • Breeds without intervention. Plan for the fry before buying mixed sexes, not afterwards.

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
Native to north-eastern South America and nearby islands — Venezuela, Guyana, Trinidad, Barbados
Habitat
Warm, hard, often mineral-rich streams, ditches and coastal drains.

What the checklists say

116 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.

StatusPlacesWhat this means
Introduced99A 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 stated17The 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.

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.

ClaimValueEvidence typeConfidenceSource
scientific namePoecilia reticulataObserved / measuredhigh confidenceCatalogue of Life; GBIF — Global Biodiversity Information Facility
native rangeNative to north-eastern South America and nearby islands — Venezuela, Guyana, Trinidad, BarbadosObserved / measuredmoderate confidenceGBIF — Global Biodiversity Information Facility
adult size3–6 cmAquarium-literature consensushigh confidenceAquariumHQ husbandry synthesis
lifespan1–3 yearsAquarium-literature consensushigh confidenceAquariumHQ husbandry synthesis
temperature22–28 °CAquarium-literature consensushigh confidenceAquariumHQ husbandry synthesis
ph7–8.5 pHAquarium-literature consensushigh confidenceAquariumHQ husbandry synthesis
general hardness8–25 °dGHAquarium-literature consensushigh confidenceAquariumHQ husbandry synthesis
minimum tank volume≥ 60 LAquariumHQ editorial positionmoderate confidenceAquariumHQ husbandry synthesis
minimum tank length≥ 60 cmAquariumHQ editorial positionmoderate confidenceAquariumHQ husbandry synthesis
minimum group size≥ 6AquariumHQ editorial positionhigh confidenceAquariumHQ 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 2026-08-11. 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. 116 distribution statements held from GBIF checklists — introduced in 94 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 sizeOne sourceBased on a verified authoritative source.1 citation, 1 independent origin

A single source: fishbase.

  • 6 cm — FishBase · Maximum recorded · The range the species is recorded from · checked 2026-08-11

What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. One authoritative source, which is what this kind of claim requires. Independent replication would be welcome and is not the standard.

What would improve this: Corroborate against a second, independent source.

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.

temperatureOne sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin

A single source: fishbase.

  • 18–28 °C — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. Derived from the observed range rather than copied from it. The observed envelope spans conditions this species meets across seasons and localities; a keeper holds one temperature continuously. The advised band trims the lower end because sustained residence at an extreme is a different demand from encountering it, and stability matters more to a captive fish than breadth.

What would improve this: Corroborate against a second, independent source.

phIndependently verifiedConfirmed by more than one independent source.2 citations, 2 independent origins

2 citations from 2 independent origins.

  • 7–8.2 pH — AquariumHQ husbandry synthesis · Recommended for keeping · Recommended for keeping · checked 2026-08-11
  • 7–8 pH — Ornamental Aquatic Trade Association · Recommended for keeping · Recommended for keeping · checked 2026-08-11Corrected on checking from 6.8–8 pH.
  • 7–8 pH — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. 2 independent origins.

What would improve this: Nothing. Recheck when the sources are next reviewed.

general hardnessIndependently verifiedConfirmed by more than one independent source.2 citations, 2 independent origins

2 citations from 2 independent origins.

  • 10–25 °dGH — AquariumHQ husbandry synthesis · Recommended for keeping · Recommended for keeping · checked 2026-08-11
  • 9–19 °dGH — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11Corrected on checking from 5–30 °dGH.
  • 8–18 °dGH — Ornamental Aquatic Trade Association · Recommended for keeping · Recommended for keeping · checked 2026-08-11Corrected on checking from 8–20 °dGH.

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. 2 independent origins.

What would improve this: Nothing. Recheck when the sources are next reviewed.

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.