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CrayfishfreshwaterModerateHigh invasive risk

Redclaw crayfish

A large tropical crayfish farmed for food across the tropics and sold to aquarists on the strength of the blue colour form. It reaches 20 cm, needs a tank most people do not have, and is established outside its native range in several countries.

Quick profile

Scientific name
Cherax quadricarinatus
Adult size
20–25 cm (7.9–9.8 in)
Lifespan
4–5 years
Temperature
22–30 °C (72–86 °F)
pH
7–8.5
Hardness
8–25 °dGH
Minimum tank
200 L (53 US gal)
Minimum length
100 cm
Swimming zone
Bottom
Social
Solitary and territorial
Diet
Omnivore
Overall confidence
moderate confidence

What keeping this species involves

Hardy and fast-growing in warm hard water. What it needs is space for a 20 cm animal and a keeper who has checked the local rules.

Warm, still and slow tropical waters including billabongs and farm dams.

Identity and names

Common name
Redclaw crayfish
Scientific name
Cherax quadricarinatus
Family
Parastacidae
Order
Decapoda
Class
Malacostraca
Also sold as
Australian redclaw, Cherax quadricarinatus, tropical blue crayfish

Adult size and growth

20–25 cm (7.9–9.8 in) — Sold at 4–6 cm. Reaches 20 cm or more in a tank with enough food.

Typical lifespan in an aquarium: 4–5 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: depressed — flattened top to bottom with a moderate. Assigned from what is typical of Parastacidae, not examined for this species.

Water and tank requirements

A 20 cm territorial decapod needs floor area and separate caves; the footprint is set by the animal's reach rather than by water depth.

Temperature (°C)

Redclaw crayfish
22–30

Scale: 0 to 36 °C.

pH (pH)

Redclaw crayfish
7–8.5

Scale: 4 to 9.5 pH.

Hardness (°dGH)

Redclaw crayfish
8–25

Scale: 0 to 30 °dGH.

The bands AquariumHQ publishes for the redclaw crayfish, each drawn against the full range this catalogue uses for that parameter. A narrow band on a wide scale is a specialist; a wide one is a genuinely tolerant animal. Source: AquariumHQ husbandry position for this record — an editorial range, not a measurement

Where these figures come from

Habitat class

Lowland floodplain

Seasonally inundated flat country — várzea, chaco, swamp margin — where the water body changes size, depth and chemistry through the year.

The habitat's defining feature is change, so a single band describes it badly. Species from here are generally tolerant of a wide range and intolerant of nothing much — which makes them easy to keep and easy to keep wrongly.

Conductivity
40–300 µS/cm
Flow
still
Dissolved oxygen
low
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 — lowland floodplain. Lowland floodplain generally runs 22–32°C, and the advised band of 22–30°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 — lowland floodplain. Lowland floodplain generally runs 6–7.5, and the advised band of 7–8.5 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 set by moulting rather than by habitat. A crayfish rebuilds its entire exoskeleton several times a year and draws the calcium for it from the water and from its own gastroliths; in soft water the moult is where the animal dies. The band is a provision for that, and it is deliberately firmer than some of these species' recorded habitat.
AquariumHQ advises
22–30
The habitatLowland floodplain
22–32

Scale: 20.5 to 33.5 °C.

Temperature: AquariumHQ's advised band against the habitat it is drawn from. Source: AquariumHQ advised range; habitat envelope is AquariumHQ's summary of the general limnology for this class of water body.
AquariumHQ advises
7–8.5
The habitatLowland floodplain
6–7.5

Scale: 5.6 to 8.9 pH.

pH: AquariumHQ's advised band against the habitat it is drawn from. Source: AquariumHQ advised range; habitat envelope is AquariumHQ's summary of the general limnology for this class of water body.
RequirementValueNotes
Temperature22–30 °C (72–86 °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 volume200 L (53 US gal)A floor, not a recommendation.
Minimum footprint100 cm longA 20 cm territorial decapod needs floor area and separate caves; the footprint is set by the animal's reach rather than by water depth.
Water flowlowMatch the outflow to this rather than to the filter's rating.
Lid requiredYesReduces evaporation and prevents accidents.
StructureDeep substrate, large caves and a secure cover. It rearranges everything it can lift.

Group size and social behaviour

Territorial and cannibalistic around moulting. One per tank unless the floor area is very large.

Structure
Solitary and territorial

Behaviour

  • Digs and rearranges substrate and hardscape continuously.
  • Emerges after dark to forage and is largely hidden by day.

Telling males from females

Mature males carry the red patch on the outer edge of the claw that gives the species its name; females do not.

Feeding

Diet type
Omnivore
Staples
Sinking pellets, Blanched vegetables, Frozen prawn and mussel, Leaf litter
Supplements
Calcium-rich foods for moulting

Breeding

Strategy
Female carries eggs and juveniles beneath the tail
Difficulty
straightforward
Parental care
carries eggs

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 fishhighAnything that fits in the mouth is at risk once this species reaches adult size.
Adult dwarf shrimpnear-certainCover reduces losses but rarely prevents them where the risk is high.
Shrimpletsnear-certainDetermines whether a shrimp colony can grow rather than merely persist.
Snailsnear-certainApplies to snails you wanted as well as snails you did not.
Long or trailing finsnoneFin damage is an entry point for secondary infection.
PlantsconsumesTough 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.

  • Reaches 20 cm and is sold at 5. Rehoming an adult crayfish is close to impossible.
  • Not a community animal at any size. Fish resting on the bottom are taken overnight.
  • Established outside its native range in several countries through aquaculture escape and release.

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
Northern Australia and southern New Guinea; farmed and introduced widely in the tropics
Habitat
Warm, still and slow tropical waters including billabongs and farm dams.

What the checklists say

49 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
Native1A checklist states the species occurs here naturally.
Introduced39A 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 stated9The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in.

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 nameCherax quadricarinatusObserved / measuredhigh confidenceCatalogue of Life; GBIF — Global Biodiversity Information Facility
native rangeNorthern Australia and southern New Guinea; farmed and introduced widely in the tropicsObserved / measuredmoderate confidenceGBIF — Global Biodiversity Information Facility
adult size20–25 cmAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
lifespan4–5 yearsAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
temperature22–30 °CAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
ph7–8.5 pHAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
general hardness8–25 °dGHAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
minimum tank volume≥ 200 LAquariumHQ editorial positionmoderate confidenceAquariumHQ husbandry synthesis
minimum tank length≥ 100 cmAquariumHQ editorial positionmoderate 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 2026-08-12. 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. 49 distribution statements held from GBIF checklists — native in 1, introduced in 36 countries. 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 sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin

A single source: Ahyong and Yeo 2007.

  • 250 mm — USGS Nonindigenous Aquatic Species database · Maximum recorded · Observed in the wild · checked 2026-08-29

What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. A documented maximum is held and the catalogue's typical adult range is stated separately, with the relationship between them recorded rather than collapsed. The catalogue's typical adult range already reaches the largest recorded specimen.

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.

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.