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CrayfishfreshwaterModerate

Blue moon crayfish

Described formally in 2015 from animals already circulating in the aquarium trade, with a marbled blue and cream carapace that gives it its name. The wild range is small, and almost every animal offered was taken from it.

Quick profile

Scientific name
Cherax pulcher
Adult size
10–12 cm (3.9–4.7 in)
Lifespan
3–5 years
Temperature
22–26 °C (72–79 °F)
pH
6.5–7.5
Hardness
5–15 °dGH
Minimum tank
100 L (26 US gal)
Minimum length
80 cm
Swimming zone
Bottom
Social
Solitary and territorial
Diet
Omnivore
Overall confidence
moderate confidence

What keeping this species involves

Straightforward to keep and easy to house badly. Nearly every problem reported with it is two animals in a tank with room for one.

Slow clear lowland creeks with soft substrate and submerged wood.

Identity and names

Common name
Blue moon crayfish
Scientific name
Cherax pulcher
Family
Parastacidae
Order
Decapoda
Class
Malacostraca
Also sold as
Cherax pulcher, Hoa Creek crayfish, blue moon lobster

Adult size and growth

10–12 cm (3.9–4.7 in)

Typical lifespan in an aquarium: 3–5 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 territorial animal of this size needs floor area rather than depth, with enough of it for shelters that are genuinely out of sight of each other.

Temperature (°C)

Blue moon crayfish
22–26

Scale: 0 to 36 °C.

pH (pH)

Blue moon crayfish
6.5–7.5

Scale: 4 to 9.5 pH.

Hardness (°dGH)

Blue moon crayfish
5–15

Scale: 0 to 30 °dGH.

The bands AquariumHQ publishes for the blue moon 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

Why these ranges: Lowland New Guinea creek water is soft and near-neutral, unlike the harder water the Australian Cherax are kept in. The difference matters: this species is regularly given yabby husbandry and the hardness is the part that is wrong.

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.

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 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.
RequirementValueNotes
Temperature22–26 °C (72–79 °F)Stability matters more than hitting an exact figure.
pH6.5–7.5A stable pH outside the ideal band is usually better than an unstable one inside it.
General hardness5–15 °dGHCheck your supplier's published figure before choosing species.
Minimum volume100 L (26 US gal)A floor, not a recommendation.
Minimum footprint80 cm longA territorial animal of this size needs floor area rather than depth, with enough of it for shelters that are genuinely out of sight of each other.
Water flowlowMatch the outflow to this rather than to the filter's rating.
Lid requiredYesThis species jumps.
StructureSand, wood and one cave per animal. Line of sight between shelters is what turns a territory dispute into a fight.

Group size and social behaviour

Holds a shelter and defends it. Pairs coexist in a large enough footprint; three in a small one does not end well.

Structure
Solitary and territorial

Behaviour

  • Rearranges substrate and wood nightly, so a layout is a suggestion rather than a design.
  • Colour intensity varies with moult stage; a dull animal is usually approaching a moult rather than unwell.

Feeding

Feeds on plant matter more than most Cherax and will strip soft-leaved plants entirely. Calcium is essential for moulting.

Diet type
Omnivore
Staples
Sinking pellets, Blanched vegetables, Leaf litter, Frozen foods, Cuttlebone

Breeding

Strategy
Direct development — the female carries eggs and then juveniles beneath her tail
Difficulty
straightforward
Parental care
bearer

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.
SnailshighApplies 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.

  • Freshly moulted animals are defenceless for a day or more and must be able to hide completely.
  • The wild range is small and the trade is largely supplied from it. Captive-bred stock exists and breeding is achievable.
  • Will take sleeping fish from the substrate at night. A tank that seems peaceful by day may not be.

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
A small area of West Papua, Indonesia
Habitat
Slow clear lowland creeks with soft substrate and submerged wood.

What the checklists say

3 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
Introduced1A 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 stated2The 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 nameCherax pulcherObserved / measuredhigh confidenceCatalogue of Life; GBIF — Global Biodiversity Information Facility
native rangeA small area of West Papua, IndonesiaObserved / measuredmoderate confidenceGBIF — Global Biodiversity Information Facility
adult size10–12 cmAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
lifespan3–5 yearsAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
temperature22–26 °CAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
ph6.5–7.5 pHAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
general hardness5–15 °dGHAquarium-literature consensusmoderate confidenceAquariumHQ husbandry synthesis
minimum tank volume≥ 100 LAquariumHQ editorial positionmoderate confidenceAquariumHQ husbandry synthesis
minimum tank length≥ 80 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 2026-08-13. 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. 3 distribution statements held from GBIF checklists — introduced in 1 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.