Red Swamp Crayfish

About

Where you live decides almost everything about this crayfish, so start there: in the European Union it is a listed invasive species and keeping one is restricted, while in the southern United States it is a food crop worth more than $150 million a year. The page exists so that someone who has just seen one in a shop can find out which of those applies to them. Commission Implementing Regulation (EU) 2016/1141 adopted the first list of invasive alien species of Union concern on 13 July 2016, and its Annex names 'Procambarus clarkii Girard, 1852' in plain text. What the listing means is set out in Regulation (EU) No 1143/2014, Article 7(1): a listed species shall not intentionally be brought into the territory of the Union, kept 'including in contained holding', bred, transported, placed on the market, used or exchanged, permitted to reproduce, or released into the environment. Underneath the law is an extremely capable animal. USGS gives adults at 5.5 to 12 cm, over 50 g in three to five months, sexual maturity in as little as two months and a generation time of four and a half months; it tolerates pH 5.8 to 10, oxygen down to 3 ppm, salinity, pollution, and anything short of its burrow freezing or passing 35 °C, and Wikipedia notes it can sit out dry spells of up to four months. In drought its burrows reach 40 to 90 cm down to the water table, it eats aquatic plants faster than they grow, and it eats fish and snails and shrimp. Almost every quality that makes it a catastrophe in a European ditch is also what makes it easy to keep alive in a tank, which is exactly the problem.

Care

Start with the law, because in the EU it is the whole answer. Regulation (EU) No 1143/2014 is directly applicable in every member state, so the Article 7(1) restrictions on keeping, breeding, transport, sale, exchange and release apply in Lithuania the same way they apply in Spain, whether or not a shop is still offering the animal. The Regulation carries its own narrow exits and they are worth knowing rather than guessing at: Article 31 lets a non-commercial owner keep a companion animal already held before its listing until the end of its natural life, provided it stays in contained holding with reproduction and escape made impossible; Article 32 gave commercial keepers two years from listing to run stock down and one year to sell live animals to non-commercial buyers; and Article 8 covers research and ex-situ conservation permits. This entry is not legal advice and the dates matter — check the rule where you actually are. Lithuania is the case worth spelling out, because two different documents get confused. The EU Union list and the Invazinių Lietuvoje rūšių sąrašas are separate instruments: the Ministry of the Environment's own combined table lists Klarko vėžys with the 2016-08-03 Union-list date and nothing in the Lithuanian column, while the signal and spiny-cheek crayfish beside it carry both dates and the note 'Lietuvos invazinė rūšis'. Absence from the national list changes nothing here, because the EU Regulation already covers it. Outside the EU the answer really does flip. In England and Wales the government guidance requires a permit from Natural England or Natural Resources Wales to introduce, hold, keep or sell red swamp crayfish; in the United States it appears nowhere in the federal injurious-wildlife listing at 50 CFR 16.13, so it is a state question, and it is simultaneously a major farmed food crop — USGS puts Louisiana industry profits above $150 million a year, and Wikipedia calls China the world's leading producer of farmed crayfish. If you are somewhere it is lawful, the husbandry is short. One adult, alone, in at least 90 litres with 80 cm of floor: Shrimp and Snail Breeder asks 20 gallons per crayfish and warns that even with space 'there is no guarantee that the crayfish will not act in a territorial manner attacking and even eating their tank mates'. A tight lid, because crayfish are excellent escape artists. A few inches of sand or fine gravel, because it will dig. Hard, alkaline water for clean molts. No plants, no shrimp, no snails and no fish worth keeping. And never release it, anywhere.

Diet

Opportunistic omnivore that becomes more herbivorous as it grows. Sinking crustacean pellets, algae wafers and blanched vegetables as a base, occasional protein, and calcium in the water and the food for molting. It will also eat the plants, the snails and the fish.

Telling males from females

There is no reliable way to sex this species by eye. That is the honest answer, not a gap in our data.

Also in these lists

Similar species

Same category and the closest water parameters — if this species isn't quite it, start here.

Sold in Lithuania

These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.

These links are unpaid: we get nothing for them and ask for nothing.

Frequently asked questions

What tank size does a Red Swamp Crayfish need?

A Red Swamp Crayfish needs an aquarium of at least 90 litres (23.8 US gallons) with a footprint at least 80 cm (31.5 in) long — for this species, swimming length matters as much as raw volume.

What water parameters does a Red Swamp Crayfish need?

Red Swamp Crayfish does best at 10–30 °C (50–86 °F), pH 6–9 and a general hardness of 3–22 °dGH.

Is the Red Swamp Crayfish suitable for beginners?

Yes — Red Swamp Crayfish is one of the easier species to keep and forgives typical first-tank mistakes, as long as the aquarium is cycled and maintained.

Sources

• Commission Implementing Regulation (EU) 2016/1141 — Annex, list of invasive alien species of Union concern (legislation.gov.uk reproduction of the adopted text)
• Regulation (EU) No 1143/2014, Article 7 — Restrictions (text as adopted, legislation.gov.uk)
• Regulation (EU) No 1143/2014, Article 31 — Transitional provisions for non-commercial owners (text as adopted, legislation.gov.uk)
• LR aplinkos ministerija — Sąjungai susirūpinimą keliančių invazinių svetimų rūšių sąrašas ir į jį įrašytų rūšių naudojimo reglamentavimas Lietuvoje
• LR aplinkos ministerija — Sąjungai susirūpinimą keliančių invazinių svetimų rūšių, Lietuvos invazinių rūšių sąrašas (bendra lentelė, PDF)
• Wikipedia — List of invasive alien species of Union concern
• Invasive Species Northern Ireland — Consolidated List of IAS of Union Concern (July 2025, PDF)
• USGS Nonindigenous Aquatic Species — Procambarus clarkii (Red Swamp Crayfish)
• Shrimp and Snail Breeder — Procambarus clarkii: Detailed Guide, Care, Diet, and Breeding
• Wikipedia — Procambarus clarkii
• GOV.UK — Introduce or keep non-native fish and shellfish (applies to England and Wales)
• eCFR — 50 CFR 16.13, importation of live or dead fish, mollusks, and crustaceans (current text)