CrayfishfreshwaterModerate

Red swamp crayfish

One of the most damaging freshwater invasive species in the world, farmed for food, sold as an aquarium animal, and named individually on the EU list of invasive alien species of Union concern. It burrows through banks, eats everything, and carries the crayfish plague that has removed native European crayfish from whole river systems.

Quick profile

Scientific name: Procambarus clarkii
Adult size: 12–15 cm (4.7–5.9 in)
Lifespan: 2–5 years
Temperature: 15–28 °C (59–82 °F)
pH: 7–8.5
Hardness: 6–25 °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

Physically among the easiest animals in this catalogue to keep alive, and among the hardest to keep responsibly. Every requirement it has is about containment.

Almost any still or slow fresh water, including seasonal and degraded sites it can burrow through.

Identity and names

Common name: Red swamp crayfish
Scientific name: Procambarus clarkii
Family: Cambaridae
Order: Decapoda
Class: Malacostraca
Also sold as: Louisiana crawfish, Procambarus clarkii, red swamp crawfish

Adult size and growth

12–15 cm (4.7–5.9 in)

Typical lifespan in an aquarium: 2–5 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 Cambaridae, not examined for this species.

Water and tank requirements

A large, territorial, burrowing decapod needs floor area and its own shelter; a moulting animal must be able to get away from every other one.

Temperature (°C)

Red swamp crayfish

15–28

Scale: 0 to 36 °C.

pH (pH)

Red swamp crayfish

7–8.5

Scale: 4 to 9.5 pH.

Hardness (°dGH)

Red swamp crayfish

6–25

Scale: 0 to 30 °dGH.

The bands AquariumHQ publishes for the red swamp 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

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 15–28°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 7–8.5 is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species. A source does publish a figure for this parameter, and it answers a different question — an environmental range or a laboratory tolerance rather than a keeping recommendation. It is held alongside this band rather than behind it.
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

15–28

The habitatTemperate still water

2–28

Scale: -1.9 to 31.9 °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 habitatTemperate still water

6.5–8.2

Scale: 6.2 to 8.8 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.

Requirement	Value	Notes
Temperature	15–28 °C (59–82 °F)	Stability matters more than hitting an exact figure.
pH	7–8.5	A stable pH outside the ideal band is usually better than an unstable one inside it.
General hardness	6–25 °dGH	Check your supplier's published figure before choosing species.
Minimum volume	100 L (26 US gal)	A floor, not a recommendation.
Minimum footprint	80 cm long	A large, territorial, burrowing decapod needs floor area and its own shelter; a moulting animal must be able to get away from every other one.
Water flow	low	Match the outflow to this rather than to the filter's rating.
Lid required	Yes	Reduces evaporation and prevents accidents.
Structure	Deep substrate it can dig, several separate caves, and a fully secure cover. It climbs equipment and leaves open tanks.

Behaviour

Burrows extensively and rearranges or undermines everything in the tank.
Climbs filter pipes and cables and leaves an uncovered tank.

Telling males from females

Mature males carry disproportionately long claws and a pair of hardened appendages behind the walking legs; females are broader through the tail.

Feeding

Eats plants, invertebrates, fish eggs and any animal slow enough to catch.

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

Breeding

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

Extremely fecund and matures fast, which is a large part of why it establishes wherever it is released.

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
Towards	Risk	What it means
Small fish	high	Anything that fits in the mouth is at risk once this species reaches adult size.
Adult dwarf shrimp	near-certain	Cover reduces losses but rarely prevents them where the risk is high.
Shrimplets	near-certain	Determines whether a shrimp colony can grow rather than merely persist.
Snails	near-certain	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	consumes	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.

Not a community animal. It takes fish that sleep on the bottom, strips planting and eats other invertebrates.
A carrier of Aphanomyces astaci, the crayfish plague, which is lethal to European native crayfish and is spread by water as well as by animals. Never release it and never dispose of tank water, substrate or plants into drains or natural water.
Turns on its own kind while the shell is soft, so shelters have to outnumber the animals rather than merely exist.

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 the south-central United States and north-eastern Mexico; introduced and invasive across Europe, Africa and Asia
Habitat: Almost any still or slow fresh water, including seasonal and degraded sites it can burrow through.

What the checklists say

107 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
Native	1	A checklist states the species occurs here naturally.
Introduced	92	A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal.
Recorded as invasive	1	A checklist states the species is invasive here. AquariumHQ reproduces that assessment; it does not make one.
Recorded as present, establishment means not stated	13	The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in.

Legal status and responsible practice

Restriction note

This species appears by name on the EU Union list of invasive alien species of Union concern under Regulation (EU) No 1143/2014, an annex AquariumHQ read directly; it names crayfish individually and Procambarus clarkii is among them. A Union listing carries bans on keeping, breeding, transporting, selling and releasing. England and Wales adds an older and separate restriction, the Crayfish (Prohibition of Keeping) Order 1996, which licenses the keeping of any Astacidae, Cambaridae or Parastacidae — this is a cambarid. It is regulated as a pest in a number of jurisdictions outside Europe as well. None of this is legal advice; check with the national authority for your own country first.

Where this species has been introduced, and what followed

Two databases on two continents hold records for this species, and they are not two accounts of one event. They are separate introductions with separate causes, and the differences between them are the most informative thing on this panel.

United States outside its native range, and worldwide

Established

NAS attributes non-native United States populations to release from aquaculture or from the aquarium trade, notes that the species' red colour has led to it being advertised as a freshwater 'lobster' for aquariums, and records that it is readily available through the biological supply trade and may be released following classroom or laboratory use.

Escape from food or bait aquacultureFood and bait production, at a scale no private keeper approaches. The animals are held in numbers, in ponds, often on floodplains.
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.
Release after classroom or laboratory useAnimals sold to schools and universities for dissection or observation, released afterwards by somebody who did not want to kill them.
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.

What has been established

Loss of aquatic plantsMeasured in studyReduces macrophyte density through feeding and macrophyte diversity through selective consumption.USGS Nonindigenous Aquatic Species database credits: Cronin et al. 2002; Smart et al. 2002
Predation on native speciesMeasured in studyConsumes the egg masses and juveniles of the threatened California newt, the endangered razorback sucker and the native natterjack toad.USGS Nonindigenous Aquatic Species database credits: Gamradt and Kats 1996; Mueller et al. 2006; Cruz et al. 2006
Competition with native speciesReported in the literatureNAS states that it outcompetes not only other native crayfish but a wider range of native biota, and cites competition as a distinct impact category alongside predation and herbivory. AquariumHQ read the sentence and not the underlying studies, so this is recorded as reported rather than measured.USGS Nonindigenous Aquatic Species database credits: Mueller et al. 2006; Gherardi and Daniels

The classroom route is the one nobody plans for. A crayfish bought for a school project has a keeper at the end of term who did not choose it and does not want to kill it, and that is a documented pathway rather than a hypothetical one.

USGS Nonindigenous Aquatic Species database · Species Profile — Means of Introduction; Species Profile — Impact of Introduction · read 2026-08-29. A United States database: the routes and effects recorded here are the ones documented there, and say nothing about other regions.

Europe — recorded in 24 countries, first in Spain in 1973

Established

EASIN names six pathways and ranks them. Aquaculture escape carries no uncertainty flag: the species was imported to Spain in 1973 to be farmed, and the European invasion begins there. The pet and aquarium pathway is recorded and flagged HIGH uncertainty — EASIN is saying the aquarium route is plausible and not established. Ornamental use, food contamination, hull fouling and unaided spread from established populations complete the list.

Escape from food or bait aquacultureFood and bait production, at a scale no private keeper approaches. The animals are held in numbers, in ponds, often on floodplains.
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.
Spread from an existing introduced populationMovement along connected water from a population already established. This is why a single introduction is not a single event.

What has been established

Physical alteration of habitatMeasured in studyRated a HIGH negative impact on inland waters. The species burrows into banks and levees, and the same behaviour is what earns it a MEDIUM rating against infrastructure.EASIN — European Alien Species Information Network credits: Vedia & Miranda-Ferreiro (2013), Review of the state of knowledge of crayfish species in the Iberian Peninsula
Carries parasites or pathogensMeasured in studyRated HIGH against animal health. The North American crayfishes carry Aphanomyces astaci, the crayfish plague, to which the European noble crayfish has no resistance. This is the mechanism behind most European crayfish policy and it is not about competition.EASIN — European Alien Species Information Network credits: Reynolds (2011), A review of ecological interactions between crayfish and fish, indigenous and introduced, Knowledge and Management of Aquatic Ecosystems 401:10
Damage to crops or aquacultureMeasured in studyRated HIGH against agriculture, specifically in Mediterranean rice cultivation, where the animal both damages the crop and uses the flooded fields as habitat.EASIN — European Alien Species Information Network credits: Clavero, López, Franch, Pou-Rovira & Queral (2015), Use of seasonally flooded rice fields by fish and crayfish in a Mediterranean wetland, Agriculture, Ecosystems & Environment 213:39-46

Listed as of Union concern: keeping, breeding, transporting, selling and releasing are prohibited across the EU. Anyone who finds they hold one should contact their national authority rather than dispose of it.

EASIN — European Alien Species Information Network · EASIN catalogue record R12250 (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.

What AquariumHQ has recorded, by jurisdiction, with the instrument each entry comes from and how far the check went. Ecological risk and legal status are separate: a species can be ecologically risky and legally unrestricted, or restricted where it could never establish.

JP

Permittedpossession

Keeping Procambarus clarkii as a household pet remains lawful without permission. The 2023 Cabinet Order placed the species in a category created for it, in which the ordinary prohibitions on keeping and on transferring to a small number of acquaintances are disapplied while every other restriction continues to apply.

Instrument: Act on the Prevention of Adverse Ecological Effects Caused by Designated Invasive Alien Species (Act No. 78 of 2004), as amended 2022 — conditionally designated invasive alien species (条件付特定外来生物), Cabinet Order in force 1 June 2023

The reason matters as much as the rule. Both species placed in this category are already established across Japan and kept in very large numbers, and a prohibition on keeping would have caused a mass release on the day it commenced. The regulation was written around the behaviour it would otherwise have produced. Every other crayfish in this catalogue is prohibited to pet keepers in Japan; this one, the most invasive of them there, is not.

Checked against the instrument · last checked 2026-08-30 · An editor has read the current text of the named instrument and confirmed this species' entry on the date shown.

JP

Prohibitedsale

Selling or distributing live Procambarus clarkii for pet, ornamental or angling-bait purposes is prohibited. Sale for restaurant, research, exhibition or educational use requires prior permission and is available only to businesses established before the designation.

A grace period ran to 30 November 2023 for businesses trading before the designation.

Checked against the instrument · last checked 2026-08-30 · An editor has read the current text of the named instrument and confirmed this species' entry on the date shown.

JP

Prohibitedimport

Import requires permission, which is not granted for pet-keeping purposes.

Checked against the instrument · last checked 2026-08-30 · An editor has read the current text of the named instrument and confirmed this species' entry on the date shown.

JP

Prohibitedrelease

Release into the wild is prohibited. The conditional designation disapplies the keeping restriction and does not touch this one; a keeper who no longer wants the animal must rehome it privately or have it euthanised.

Penalties under the Act reach three years' imprisonment or a fine of three million yen for an individual.

Checked against the instrument · last checked 2026-08-30 · An editor has read the current text of the named instrument and confirmed this species' entry on the date shown.

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	Procambarus clarkii	Observed / measured	high confidence	Catalogue of Life; GBIF — Global Biodiversity Information Facility
native range	Native to the south-central United States and north-eastern Mexico; introduced and invasive across Europe, Africa and Asia	Observed / measured	moderate confidence	GBIF — Global Biodiversity Information Facility
adult size	12–15 cm	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
lifespan	2–5 years	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
temperature	15–28 °C	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
ph	7–8.5 pH	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
general hardness	6–25 °dGH	Aquarium-literature consensus	moderate confidence	AquariumHQ husbandry synthesis
minimum tank volume	≥ 100 L	AquariumHQ editorial position	moderate confidence	AquariumHQ husbandry synthesis
minimum tank length	≥ 80 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. 107 distribution statements held from GBIF checklists — native in 1, introduced in 61, recorded invasive in 1 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 sourceBased on a verified authoritative source.1 citation, 1 independent origin

A single source: GIS 2011; Henttonen and Huner 1999.

5.5–12 cm — USGS Nonindigenous Aquatic Species database · Typically observed · 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 source publishes a typical adult size for this species, separately from any maximum. That is the quantity this claim is about.

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 would improve this: Go and read a source. This is reachable and has not been reached.

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

A single source: Huner and Barr 1991.

5.8–10 pH — USGS Nonindigenous Aquatic Species database · Tolerated range · Observed in the wild · checked 2026-08-29

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. The advised band does not rest on the observation held. 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 7–8.5 is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species. A source does publish a figure for this parameter, and it answers a different question — an environmental range or a laboratory tolerance rather than a keeping recommendation. It is held alongside this band rather than behind it.

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

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 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 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.

Predator and prey sizeIt takes fish that fit in its mouth, and its mouth grows with it.
Territorial behaviourIt defends ground, and the shape of what it defends decides the tank more than the volume does.
Native, introduced and invasiveThis record carries an invasive or legal note, and those are five separate claims that are easy to read as one.
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.
What a legal restriction on a species actually meansAquariumHQ holds a structured legal status for this species, and possession, sale, import and release are four separate questions.

Red swamp crayfish

Quick profile

What keeping this species involves

Identity and names

Adult size and growth

Water and tank requirements

Where these figures come from

Group size and social behaviour

Behaviour

Telling males from females

Feeding

Breeding

Tankmates and compatibility

Assessed pairings

Welfare considerations

Problems to watch for

Where it comes from

What the checklists say

Legal status and responsible practice

Where this species has been introduced, and what followed

United States outside its native range, and worldwide

What has been established

Europe — recorded in 24 countries, first in Spain in 1973

What has been established

JP

JP

JP

JP

Evidence

Why we say this

Guides relevant to this species