Red swamp crayfish

Water parameters

Minimum tank: 100 L per individual at harvest size.

Feed and growth

Feed protein

25% target

Daily feed (warm)

2.20% of body weight

Daily feed (cool)

0.80% of body weight

Max density

30 g per litre

A 80 g adult eats about 1.8 g of feed per day at optimum. 10 fish at adult size: ~18 g daily.

Legality

Rules vary by jurisdiction and change over time. Verify with your local fisheries or wildlife authority before stocking.

Unlisted jurisdictions default to "check local regulations".

Origin and habitat

Native to the south-central United States, from Texas and Louisiana east into Mississippi and Alabama and on into northeastern Mexico, where it lives in swamps, marshes and slow rivers. It is the most commercially important crayfish on earth. Louisiana's long-established crawfish industry runs well over a hundred thousand tonnes and more than 150 million dollars a year, but global output is now dominated by China, where production has reached roughly 2.9 million tonnes. Adults are modest in size, about 7–12 cm and 50–80 g. The species is remarkably tough: it handles water from near freezing to about 35°C, burrows into mud to ride out drought, breeds quickly and sets up self-sustaining populations almost anywhere it lands. It has become the dominant freshwater crayfish across much of Europe, Japan, China and East Africa, where it displaces native crayfish and reshapes the systems it invades.

Climate and outdoor ponds

Climate

subtropical (tolerates mild cooling)

USDA zones

7–13 (winter low around -18°C or warmer)

Heating needed

no

Cooling needed

no

Care notes

The most productive freshwater crayfish for warm-water culture, but tightly regulated outside its native range because it spreads so aggressively. It grows fast in warm water, reaching market weight in only a few months, quicker than any other commonly farmed crayfish, on crayfish or catfish pellet of about 25 to 32 percent protein with feed conversion around 1.5 to 2.5; it also scavenges detritus, waste feed and decaying plant matter. Stock by bottom area, roughly 15 to 25 animals per square metre. Breeding is prolific: the female broods eggs under her tail and the young hatch as independent miniatures with no larval stage, so a colony renews itself fast and can become hard to contain. Water-quality tolerance is wide, helped by low-oxygen endurance, a broad pH band and burrowing. The real issue is legality and biosecurity. P. clarkii carries crayfish plague, the oomycete Aphanomyces astaci, which has destroyed native crayfish across Europe, and it also spreads the amphibian chytrid fungus, so it is banned or restricted across most of the US outside the Gulf states, throughout the European Union, and in Australia and many other countries. Where culture is allowed, containment such as screened drains and a ban on outdoor ponds is usually required. Louisiana and the wider Gulf region remain the main areas open to unrestricted farming.

Further reading

• Fish for aquaponics: tilapia vs everything else