Can Fish Drown? (The Answer Explained)

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If your answer to the question ‘Can fish drown’ is “No” then congratulations, you are right.

No, fish cannot drown in water.

‘Drowning’ is more appropriate for air-breathing animals.

Thus, a more precise question would be: Can fish suffocate?

The answer to that is a firm “Yes”.

Suffocation is a condition of being deprived of oxygen and fish need oxygen to breathe.

Drowning indicates dying due to inhalation of water, a process fish do regularly but for a different reason.

Can fish suffocate

When water flows through the gills, of the aquatic respiratory organs, the oxygen dissolves and enters their blood, thus enabling a fish to breathe.

Therefore, they are physically incapable of drowning but they can suffocate.

Small technicalities, but it makes a huge difference when you want to avoid this happening.

If this is a bit confusing for you, this article will help you to explore the topic thoroughly of how fish breathe underwater.

I will also explore the topic of, do fish have lungs and what is the role of oxygen in their lives.

If you are ready, let us dive right in.

Do Fish Have Lungs? 

Do fish have lungs

Most fish do not have lungs.

As mentioned before, they use gills to breathe underwater.

The gills are the fish’s respiratory system. 

Just like mammals, they need a constant supply of oxygen to live.

Oxygen enables them to use the energy from consumed food in a chemical reaction that happens within all cells.

In order to live, breathe, and swim in the water, fish need gills to help them use the power of oxygen.

There is however a group of fish that do have lungs.

These fish are referred to as ‘living fossils’.

These are evolutionary very important species because they have remained unchanged since the time they appeared.

This group of fish is called ‘lungfish’.

Lungfish are fish that, in addition to breathing through their gills, also have a well-circulated swimming bladder that acts as a lung so they can inhale oxygen from the air.

Thanks to this adaptation, they can survive adverse conditions like being buried in mud.

Lungfish live in rivers and swamps of tropical areas in South America, Africa, and Australia.

Another group of fish that can breathe air is the labyrinth fish.

This group of fish includes gourami and betta fish.

The labyrinth organ allows them to take oxygen from the air instead of from the water and acts like a lung.

This organ lets them live in polluted and low-level oxygen waters.

Can fish suffocate under these conditions?

Yes, and that is why they developed this special organ.

For fish in such habitats, having a labyrinth organ can mean the difference between life and death.

Do Fish Drink Water?

Do fish drink water

The answer to this question depends on the type of fish we are talking about.

Is it freshwater or marine?

The difference is something called osmosis.

Basically, molecules in water move from a low salt concentration region to a high salt concentration region.

The body of freshwater fish is saltier than the water in which they live, so their bodies constantly absorb water by osmosis through their gills.

Therefore, drinking water would be counterproductive for them, and they do not drink it.

All the water that ends up in their mouths, gets thrown out.

As for marine fish, their body is less salty than the water they swim in, which means that their body is constantly losing water, thus they have to ‘drink’ it to prevent dehydration.

Unlike us, fish can successfully filter salt from seawater so it does not harm them.

How Do Fish Breathe?

We have already mentioned their most important organ, their gills. 

Fish live in water, so their respiratory organs are built differently from those of other vertebrates.

Fish breathe with gills built of well-circulated parts called gill slits.

Water with dissolved oxygen enters through the mouth and passes through the gills where oxygen diffuses into the capillaries.

The heart then pumps this blood through their bodies.

When a fish lowers its mouth, the pressure inside the mouth becomes lower than the pressure outside the mouth.

The water then flows in and passes over the gills allowing the oxygen to diffuse into the blood vessels.

When the fish closes its mouth, the pressure inside becomes higher than outside, resulting in the water flowing out. 

This is what happens when you look at a fish opening and closing its mouth.

How Long Can A Fish Live Out Of Water?


Most fish will suffocate and die when taken out of water.

This happens because their gill slits collapse and stop providing their blood vessels with vital oxygen.

It is very distressing for a fish to spend time outside of water.

As it has no access to oxygen, it will start to suffocate and gasp for air.

However, some types of fish can breathe out of water and these fish will last a lot longer than fish that only have gills.

Another factor to consider is metabolism.

Fish with slow metabolisms that live in cold water can survive for a longer time.

This is because their oxygen demand and metabolic rate are lower than those in warm water fish.

Most pet fish found in home aquariums have small bodies and fragile gills.

If there is no gill movement happening within 3 to 4 minutes then they will suffocate and die.

If your fish is lucky when jumping out of the tank and happens to land on a liquid surface then the water will help to keep its gills moist.

Hopefully, it can give you enough time to save it before it starts to suffocate.

There are some fascinating fish that can survive for long periods of time out of water.

Examples are the Mangrove Killifish.

This interesting fish is amphibious and it can last for nearly a month without any water.

They draw oxygen out of the air via their skins and can even store oxygen.

They start to use their gills again when they are back in the water.

The Walking Catfish has an extra organ that enables it to breathe air just like we do.

They are able to ‘walk’ on land by flexing their bodies and using their pectoral fins to propel themselves forward.

Most catfish just need to stay moist to survive for at least 15-18 hours.

Another amphibious fish is the Mudskipper.

These fascinating fish can survive on land for almost their entire lives.

They have blood vessels near the surface of their skin that draws oxygen into their bloodstream.

The Snakehead fish can easily stay alive for up to 6 days with some specimens going as long as 6 months without water.

It too can travel over land in search of a new habitat.

Coming back to the question of how long a fish can live without water?

Most fish found in the home aquarium will die within minutes of being out of water.

It causes them extreme stress and they will suffer so it is best to not allow this to happen.

Do Fish Need Oxygen?

do fish need oxygen

Oxygen is the most critical element, without which living beings, fish included, cannot live.

Oxygen is dissolved in the water from the atmospheric air, surface agitation, and the photosynthesis of plants. 

The dissolved oxygen content allows the fish to breathe, digest, feed, develop, reproduce, and stay in good health.

The amount of oxygen present in the water changes depending on the water temperature.

The warmer the water, the less oxygen it holds.

The colder the water, the greater the amount of oxygen that will be present.

Large bodies of water have more oxygen which means this is a challenge for fish owners.

Most of you already know that the correct tank size is essential for keeping fish healthy.

Your fish tank at home is an enclosed environment meaning that it requires your input to keep the habitat stable and safe for your fish.

Symptoms of Low Oxygen In The Fish Tank

Now that you have enough information on if a fish can drown and why oxygen is so important for their development, it is crucial that there is sufficient oxygen in your fish tank.

If there is not enough oxygen then the fish will be sluggish and hardly move.

They will also spend more of their time near the surface, gasping for air.

If this happens, then you need to act quickly to save your fish.

Do an immediate 50% water change.

The fresh water will introduce new levels of oxygen and help your fish to breathe.

This will give you time to find the cause of the problem.

Check for some of the usual causes of lower oxygen levels like:

  • too many fish in too small a fish tank
  • a lack of water movement that stops the oxygen exchange
  • higher water temperature that does not hold the oxygen as colder temperature water does
  • excess waste and debris that causes a decrease in dissolved oxygen
  • reduced light levels. 

While many factors play a role in decreased oxygen levels, the most important thing is to change the water immediately, then look for the direct cause of lower oxygen levels.

Here are some suggestions on how to ensure that your fish tank has enough oxygen:

  • Make sure your fish tank is the correct size.
  • Do not overcrowd the tank with too many fish.
  • Slowly pour water into the tank so it absorbs oxygen from the air.
  • Increase the water movement by adding a power head, bubbler, or additional filter.
  • Increase the lighting if you have live plants inside the tank.
  • Do not use chemicals that can lower oxygen levels.

Summary – Can Fish Drown?

We started with the question “can fish drown”, and ended with the importance of oxygen for their metabolism processes.

 Although we concluded that fish cannot drown, they can suffocate if left without oxygen for some time or if the oxygen levels are too low.

Their gills are meant to be used in the water, and any change to their natural habitat can cause them to suffer.

Fish need oxygen to exist.

Purposely leaving a fish out of water is inhumane and cruel.


Can water drown fish?

Fish can suffocate if the water they are in lacks sufficient oxygen, as they rely on dissolved oxygen to breathe. Factors such as overcrowding, algae blooms, or poor water circulation can deplete oxygen levels, leading to a condition where fish are unable to extract the oxygen they need, causing them to “drown.”

How do you know if a fish is drowning?

Determining if a fish is “drowning,” or suffering from a lack of oxygen, can be seen with signs such as gasping at the water’s surface, lethargy, and unusual swimming patterns. Regular testing of water oxygen levels, along with keeping an eye on the fish’s behavior, can help in early detection and prevention of this potentially harmful situation.

Can fish feel pain?

Scientific studies have indicated that fish possess nerve receptors called nociceptors, allowing them to sense and respond to harmful stimuli. While it’s still a debated subject, evidence suggests that fish can indeed feel something akin to pain, though it may not be experienced in the same way that mammals perceive it.

Do fish get thirsty?

Fish do not experience thirst in the way that land animals do, as they live in an environment surrounded by water. Freshwater fish absorb water through their skin and gills, while saltwater fish actively drink sea water, with specialized cells to excrete excess salt, so the concept of thirst doesn’t apply to them in the traditional sense.

Photo of author


Irma Bense is the founder of She has over 42 years of experience in keeping fish.She has kept both freshwater and saltwater fish through the years.She has extensive knowledge in breeding numerous species of fish from Show Guppies, Cory Catfish, German Blue Rams to Apistogrammas.You can learn more about Irma on the 'About' page.

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