How Long Can a Fish Live Out of Water?

Have you heard the expression, “like a fish out of water?” That old saying refers to someone who is uncomfortable in a particular situation. 

If you ever had a fish jump out of its tank, you’ll have seen it flapping around on your floor, clearly desperate to find water. That’s where the expression comes from. Now, obviously, you’ll need to get your pet back into his aquarium as soon as possible. But how long can a fish live out of water? 

Keep reading to find out!

Can Fish Survive Out Of Water?

Close up view of raw bullhead fish called goby fish on big green leaf.

Most don’t have the physiology that’s necessary for them to take oxygen directly from atmospheric air. So, how long can your pet or tropical fishes survive out of their tank?

Generally, fish species, such as Neon tetras, guppies, and Rainbow sharks, can only survive for a maximum of ten minutes when out of water. The stress and shock of being out of their natural environment and the inability to breathe often reduces survival time to just a few minutes.

Most freshwater fish don’t last as long out of the water as saltwater species. That’s because freshwater pets are typically more fragile and sensitive than their marine cousins.

What Happens To A Pet Fish Out Of Water?

Removing a fish from its natural watery environment is extremely stressful for the animal. The fish has no access to usable oxygen and quickly begins to gasp for air, ultimately suffocating within a few minutes. The fish will often flap its fins as it attempts to move and find water. The fish’s gills then open and arch until it collapses and death occurs within a very short period of time.

Take Precautions!

So, be extremely careful when moving or transporting your fish. If you’re moving house or bringing new one home from the store, always place the fish in their bag of water in a leak-proof container, just in case the bag splits.

When cleaning out your tank or carrying out routine maintenance tasks, take care not to alarm the fish so that they panic and jump out of the water. Also, when introducing new fish to an established community setup, watch the fish very carefully for signs of bullying that might cause escape attempts.

Some species, such as bettas, are accomplished jumpers. So, always keep acrobatic fish in a tank that has a cover slide or tightly fitting lid.

How Do Fish Breathe Underwater?

Just like you and me, fish need to absorb oxygen and expel carbon dioxide to live. However, instead of lungs like mammals, most have gills.

Gills are branched structures that contain complex networks of tiny blood vessels called capillaries. Each time the fish opens its mouth, water flows across the gills. The blood in the capillaries extracts dissolved oxygen from the water and circulates that around the fish’s body to its vital organs and body tissues. If you notice your fish breathing very rapidly, that’s a sign that there’s not enough oxygen in the water.

Bony species have another physiological structure called the operculum. The operculum is a bony plate that opens and closes as the fish “breathes,” protecting the sensitive gills. If you keep shrimp and snails, you’ll be interested to know that they also have gills. 

Crustaceans and mollusks’ gills work in the same way as your fish’s, extracting oxygen from the water as it flows over the gills. Marine creatures, such as sea slugs or nudibranchs, have external feathery gills that protrude as brightly-colored structures from the animal’s back.

Breathing Underwater

The atmospheric air that you and I breathe contains around 200,000 parts per million (ppm) of concentrated oxygen. Compare that with water that has a concentration of only 4 to 8 ppm. As you can imagine, that means a lot of water must pass over the fish’s gills for the creature to get all the oxygen it needs. Fortunately, the gills are incredibly efficient at extracting oxygen!

“Dead Zones”

In a natural habitat where oxygen is in short supply, breathing is even more challenging for the fish. In the aquarium, hypoxic “dead zones” sometimes form in areas where the substrate becomes compacted, and water circulation is poor. In these pockets, oxygen levels are extremely low, and the water is often stagnant, harboring colonies of toxic bacteria. Too many dead zones in the aquarium can render the environment uninhabitable and devoid of oxygen, resulting in mass kills.

However, if you keep up to speed with your aquarium maintenance and cleaning tasks, including vacuuming the substrate, you can prevent dead zones from forming and threatening your fish.

In the wild environment, human activity can cause hypoxic zones to form, causing a catastrophic drop in the oxygen level. Recently, in 2019, farm run-off caused a huge dead zone to form in the Gulf of Mexico, killing thousands and putting other wildlife at risk, too.

Why Do Survival Rates Vary?

So, how come some species can survive out of water for longer than others?

There are several factors that directly affect the survival rates out of water.

Type of Fish

Some can survive for longer than others if they end up out of the water. 

For example, amphibious fish can often live for hours, days, or even years without being in the water, thanks to evolutionary physiological quirks that enable them to withstand extreme conditions. 

Metabolic Rate

Usually, fish that live in warm climates have a faster metabolic rate than those from cooler regions. The faster the animal’s metabolic rate, the more oxygen it needs to survive. So, fish that live in colder temperatures can theoretically survive out of the water for longer.

Oxygen Demands

Some aquarium fish have higher oxygen demands than others. 

Goldfish ryuikin underwater in aquarium

For example, goldfish are very oxygen-hungry, so they need a tank with plenty of surface area for good gaseous exchange and a filtration unit that generates a high flow. So, if your goldfish jumped out of your tank or pond and ended up on the carpet or decking, he most likely wouldn’t last very long.

That said, one of my goldfish was fished out of the garden pond by my cat. The fish flapped around for quite a few minutes before I managed to scoop it up and get it back into the water, miraculously none the worse for its adventure. 

Why Do Fish Leave The Water?

But why do fish leave their natural aquatic habitat in the first place?

There are a few reasons why some species feel the need to leave the water:

  • To avoid predators
  • To escape polluted or oxygen-depleted water 
  • To escape water that’s too warm
  • To find food or mates
  • To escape a changing environment where the water is drying up

Now, let’s take a look at some of the species that can actually breathe air and even survive out of the water. 

What Fish Species Can Breathe Out Of Water?

There are quite a few species that can manage just fine when out of the water for a short time. Who knew?!

Betta Fish

Betta Fish swimming

Betta and other members of the gourami family are commonly referred to as labyrinth breathers or Anabantoidei.

These have a specially adapted organ within the body cavity called the labyrinth organ. The labyrinth organ contains lots of small compartments composed of thin bony plates or lamellae. The lamellae are encased in fine, permeable membranous tissue that allows oxygen to be absorbed. The membranes contain super-fine capillaries that carry the oxygen in the blood around the body in the fish’s bloodstream.

During the dry season, when the small ponds and streams in which they live begin to dry up, betta fish can leap from one body of water to another. As long as the fish remains moist, it can survive for quite a while, thanks to the labyrinth organ. In the aquarium, you’ll often see labyrinth species visiting the water surface to take gulps of air to supplement the dissolved oxygen that they derive from the water.

Dolphins And Whales

Although they don’t possess a labyrinth organ, certain ocean-going fish can breathe atmospheric air.

Okay, so the creatures we’re referring to here are actually not fish at all, but mammals like you and me. However, these animals, including dolphins and whales, are sometimes mistaken for fish since they spend their whole lives in the water. 

These ocean-dwellers have lungs, meaning that they need to make frequent trips to the water surface to breathe via their blowhole. Once the animal has taken a breath, the blowhole closes so that water doesn’t enter the lungs when the creature is submerged. As the whale or dolphin surfaces to breathe, the blowhole opens and the animal blows to clear water from the blowhole, creating the spectacular spout you’ll have seen if you’ve ever been whale watching.

Why Don’t Whales Suffocate?

Did you know that Blue whales can remain underwater for over an hour without needing to take a breath!

Well, you breathe on average 12 to 20 times every minute while you’re just chilling out, but you only absorb around 5% of the oxygen from each breath. Whales, on the other hand, can absorb up to 90% of the oxygen from every breath they take. So, a whale takes in a whole lot more oxygen in each breath than you do, meaning that the creature doesn’t need to breathe so often.

Also, whales’ lungs can store oxygen in a protein called myoglobin that’s found in the muscles. While underwater, whales can slow their heart rate and restrict the blood supply to a few key organs, further reducing the amount of oxygen they need.

So, that’s how whales are able to stay submerged for so long.

Mangrove Killifish

The Mangrove Killifish is also known as the Mangrove rivulus and is found in parts of the Atlantic and the Caribbean. The fish lives in marine, brackish, and sometimes freshwater habitats, especially mangrove forests and estuarine waters.

These strange fish are amphibious, sometimes living on the land for up to two months and absorbing the oxygen they need through their skin.

Mudskippers

Mudskippers are also amphibious fish that happily spend much of their lives out of water. In fact, the fish are so well-adapted for life on terra firma that they have developed specially positioned pectoral fins that work like legs, enabling them to propel themselves across mudflats. Amazingly, these fish can leap over two feet, as well as climbing trees, using their fins for propulsion. 

The mudskipper’s skin contains blood vessels that can extract oxygen from the air, effectively enabling the fish to breathe right through its skin.

Walking Catfish

The Walking catfish from Southeast Asia is a large creature that can grow up to 20 inches in length. Like the Mudskipper, Walking catfish (Clarias batrachus) can use their pectoral fins to propel them across dry land in search of water during the dry season. 

As well as gills, the Walking catfish has a set of air-breathing organs that only come into play when the fish is out of water, enabling the creature to breathe atmospheric air.

Rockskipper Fish

The Rockskipper is also known as the Coral blenny (Istiblennius zebra). 

These Hawaiian freshwater fish live in exposed habitats where they live in shallow pools. To go in search of food, new territories, or mates, the Rockskipper literally skips or jumps from pool to pool.

These curious little fish are able to breathe air via reinforced cutaneous gill rods behind their gills.

Snakehead Fish

Snakeheads are common in parts of Asia and Africa. These fish are amphibious carnivores that can leave the water to hunt for prey on land. Some species of Snakehead fish can live on land for up to six days, moving across the land in search of new habitat.

Lungfish

Lungfishes are ancient creatures that inhabit freshwater habitats in Africa, Australia, and South America, depending on the species.

These descendants of the Osteichthyes are one of only a few species of fish that have the ability to breathe on land and in water, possessing both lungs and gills. When the fish’s watery home dries up during droughts, the fish can enter a dormant state, breathing solely through their lungs and surviving for up to four years until they can find water again.

Eels

eel

Eels are relatively common freshwater ray-finned fish that can negotiate obstacles while swimming upriver to spawn. The fish can derive oxygen from the air directly through their skin, enabling them to make arduous journeys from the ocean to their freshwater river breeding grounds. 

Climbing Perch

The Climbing Perch (Anabas testudineus) is found in India and China. These fish belong to the same family as gouramis, and are able to breathe out of the water, surviving for up to ten hours, as long as they remain moist.

These are popular as a food source in their native lands, largely because the fish can be kept fresh for a long time in a very small amount of water.

In Conclusion

Did you find our guide to how long a fish can live out of water helpful? If you did, please share. Also, feel free to comment in the comments box below.

If you keep tropical or marine fish, be very careful that your pets don’t jump out of your aquarium when your back is turned! Pet fish can only survive for a few minutes once out of water. Even labyrinth fish must remain moist to survive, and that won’t happen on your living room carpet!

Alison Page has been an avid fish keeper for over 35 years and has owned many different species of freshwater tropical fish including bettas. Currently Alison has two large freshwater tanks. The first tank has two huge fancy goldfish who are almost ten years old and still looking as good as ever. In the other, she has a happy community of tiger barbs, green tiger barbs, corydoras catfish, platys, and mollies.

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