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Can Crayfish Breathe Air? What Their Gills Actually Need

Crayfish breathe through gills, not lungs. Learn how long they last out of water and what that means for keeping one.

Jack·7 min read·July 13, 2021·Updated October 17, 2026

You flip a rock in a creek, a crayfish scoots backward, and you scoop it up to look. Then you wonder: is it holding its breath? Not really. Crayfish need oxygen, but they get it from water through gills, not from air through lungs. Out of water they can last for hours, sometimes days, but only while their gills stay damp. Dry gills collapse, and the animal suffocates. Below is how that breathing works, how long a crayfish can last out of water, and what this means if you catch or keep one.

How crayfish breathe underwater

A crayfish is a water-breather. Its gills sit inside a chamber on each side of its body, under the shell. The animal keeps water moving through that chamber, and the gills pull out the oxygen dissolved in it.

A 1974 study of the red swamp crayfish (Procambarus clarkii) traced how this works. Water flows through the gill chamber, while blood inside each gill filament flows the opposite way. Running the two streams against each other is an efficient way to move oxygen from water into blood. Researchers have also studied the side plates of the shell that cover the gills, called branchiostegites, for their own part in gas exchange.

Because the gills are built for water, depth is never the problem. A crayfish can live its whole life fully underwater. What can kill it is water that holds too little oxygen.

What happens when a crayfish leaves the water

Gills work only while they stay wet. In dry air, the fine filaments stick together and collapse. Once that happens, there is little surface left to take up oxygen.

A crayfish can delay this. Its shell traps a small pocket of water or humid air around the gills, which keeps them moist for a while. That is why a crayfish you lift from a creek doesn't die in a minute.

How long a crayfish can survive out of water

It depends on the species and on how humid the air is. Stream species are reported to last about a day or two in dry air. Lab tests on some native crayfish have measured survival from about 20 hours to more than 120 hours.

Shade, damp moss, or a wet bucket buy more time, because they slow the drying of the gills. Hot, dry air does the opposite.

How burrowing crayfish ride out dry spells

Some crayfish don't wait for rain. They dig. The red swamp crayfish can burrow into the ground during long dry periods, and it can also walk several miles over fairly dry ground to find new water.

In a lab study comparing several species, P. clarkii, the best burrower of the group, survived drought best. It settled underground and dropped into torpor, lowering its metabolism until conditions improved.

A burrow brings its own risk. A Griffith University study found that water in a flooded burrow ran out of oxygen within about 8 hours on average. Species that live mostly in burrows coped well with low oxygen. Species that burrow only now and then showed little to no tolerance for it. So the same habit that saves one crayfish from drying out could suffocate another.

Meet the red swamp crayfish

The red swamp crayfish is the one most people have seen, whether in a Louisiana boil, a pet store, or a ditch where it doesn't belong.

  • Size: adults are usually 2 to 5 inches long (about 5.5 to 12 cm). They mature by size, at roughly 6 to 12.5 cm.
  • Lifespan: 2 to 5 years, and often 2 years or less in the Deep South.
  • Diet: it eats almost anything, including aquatic plants, snails, insects, fish, and the eggs and young of amphibians.
  • Eggs: a 10 cm female may produce up to about 500 eggs, and smaller females around 100. Each egg is about 0.4 mm across.
  • Breeding: the female carries her eggs under her tail rather than burying them. The hatchlings stay with her in the burrow for up to eight weeks. In the southern U.S. this species can spawn year-round, and females may breed more than once a year. Where floods last more than six months, there may be two breeding seasons, in autumn and spring.

Keeping one at home

What a crayfish's gills need tells you most of what its tank needs: water that is well oxygenated, not just wet. Crayfish also roam. Keep the lid tight, with no gap big enough for the animal to squeeze through. A crayfish on the floor will stay alive for a while, but not for long.

Because red swamp crayfish eat fish in the wild, putting one in a tank with fish is a risk. That is a reasonable guess, not a tested rule, but small or slow fish would be the first to go.

Never let one go

A crayfish that can cross miles of dry ground and wait out drought underground is very good at spreading. That is why many places treat non-native crayfish as invasive. Crayfish are not federally regulated in the United States or Canada, but many states have rules of their own:

  • Minnesota bans possessing, importing, buying, selling, breeding, moving, or releasing red swamp, marbled, and yabby crayfish without a permit.
  • Ohio bans possessing, importing, releasing, or selling live marbled, marron, yabby, and red swamp crayfish.
  • Pennsylvania makes it unlawful to possess, import, sell, or buy any live crayfish, with narrow exceptions.
  • Wisconsin forbids moving, possessing, transferring, or releasing live non-native crayfish.
  • Michigan bars possessing or selling non-native species without permission.
  • Indiana lists the red swamp crayfish as a "species of concern" and requires a permit for more than 500 live crayfish that are not for sale or bait. Accounts of these rules vary, so check the state's current rules.

If you no longer want a pet crayfish, return it to the seller or give it to an aquarium or a school. Ask a vet or pet retailer about humane euthanasia only as a last resort. Don't release it, and don't move live crayfish from one creek or pond to another.

A note on the cooking pot

Whether crayfish feel pain is no longer a fringe question. In 2022, the UK's Animal Welfare (Sentience) Act added decapod crustaceans, the group that includes crayfish, lobsters, crabs, and shrimp, to the animals it recognizes as sentient. The scientific review behind the law, from the London School of Economics, concluded that boiling them alive should be banned.

England's Animal Welfare Strategy has since called live boiling unacceptable. It has not set a ban or a date for one.

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