Why Do Fishes Die When Taken out of Water? Knowing Your Fish

Joan Agie
Oct 06, 2023 By Joan Agie
Originally Published on Oct 11, 2021
Fish swimming in tank
Age: 3-18
Read time: 5.0 Min

Fishes breathe air from tiny blood vessels on the surface area of gills, not directly from the air.

Fishes live inside water but they die when taken out of water. The are several reasons for this.

No human would ever report seeing a live fish above the surface of the water after it has been out for a while. Fishes take in oxygen dissolved in water through their gills.

Gills, for fishes, are what noses are to humans. The gill of a fish cannot take in oxygen just from the air.

For them to be able to breathe, it is essential that they are underwater. Let's see what we can learn about fishes, their breathing functions underwater and what happens when they are taken out of the water.

To know more about fish, you may also like reading about how often to feed fish and when do catfish spawn.

What happens to fish when taken out of water?

Why do fish die outside water? Can a fish breathe outside water? Why is a fish content living in water?

These are all related questions and there is only one answer to them. Fishes are always found living in water. They inhabit rivers, streams, oceans, lakes. They can also live in artificially made ponds and tanks.

The natural habitat of fishes varies according to their species, but the common thing between all is water. Some fishes are saltwater fishes, while others are freshwater fishes. While devising a tank for certain fish species, care should be taken that they feel close to their natural habitat.

Fishes are always kept in water as fishes die when taken out of water. They cannot survive the overload of carbon dioxide and lack of oxygen above the surface of the water, which leads to their death.

Biology experts have drawn out the respiratory systems of fish. It happens that gills play a role in the respiratory system of fishes.

Gills are the lungs of fishes that absorb oxygen dissolved in water. But when gills come in contact with air, their function is not that efficient and fishes feel the lack of oxygen.

Hence, it is important to keep your fish in ample amounts of water to completely cover their body and leave them space to move around. After all, it is a matter of life and death.

Why do fishes die when taken out of water?

Consequence-related questions are often asked whenever there is a discussion on fishes being taken out of water and their ability to breathe in normal air. Fishes are less likely to survive outside water.

This is because of the function of their respiratory system. Fishes when brought outside water and in contact with air start moving around frantically. It is because their brain starts to feel the lack of oxygen in their bloodstream.

Their supply of oxygen eventually gets cut off if they stay out of water for too long. Lack of oxygen causes death in fishes, just like humans.

Fishes take in water through their mouths. There is a lot of dissolved oxygen in the water.

This dissolved oxygen from water is extracted by gills as soon as the water enters the fishes' bodies. The water taken in through the mouth comes out from the gills after the oxygen from water is replaced by carbon dioxide.

This process goes on continuously without interruption allowing the fish to breathe. But when a fish is taken out of water or it gets out of the water, its respiratory system completely collapses and it is unable to breathe.

Gills are not adapted to simply breathe through air. The fine threadlike structures of the gills are no more able to absorb oxygen.

This leads to a shortage of oxygen in their blood. Unlike lungs, gills cannot breathe through the air and causes disruption in the fishes' respiratory systems and hence fishes die when taken out of water.

A carp takes a breath in water

How long does it take for a fish to die when taken out of water?

Now that we have established the fact that fishes most definitely die when they come out of water, let's explore some other common questions to see if there are any chances they can survive in normal air like humans. All biological systems do not respond immediately.

There is some response time for every event. In most cases, biological components are stored to be used in case of emergencies. In fishes, a little amount of oxygen is present in their blood before they completely run out of oxygen.

As fishes lack lungs it is impossible for them to breathe above the surface of the water. Gills are only functional, and act as their lungs, inside water.

But when fishes are taken out of water there is still some oxygen in their body which their brain can use to retain as many functions as it can and at the same time give out carbon dioxide. It takes time for the oxygen to get used up.

Until it happens, fishes can survive above water. The time for the oxygen to get used up varies from species to species.

What to do if a fish is out of water?

It is essential that you try to get your fish back into the water as soon as you spot them outside the water. If your fish feels rigid then under no circumstances try to wiggle them.

This may cause stress and tear in their muscles. Gently pick up your fish and take it to a clean water source. Hold them in clean water and check for breathing through the movement of their gills.

It might take a few seconds for them to move their gills. If even after half a minute your fish is not breathing you will have to make their gills move for them. Do not touch the gills directly since they are fragile.

Use a syringe to pump water in the fish's mouth and let it flush out through the gills. Continue this till the fish is able to move its gills on its own.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for why do fishes die when taken out of water, then why not read about where silverfish come from and catfish facts?

We Want Your Photos!
We Want Your Photos!

We Want Your Photos!

Do you have a photo you are happy to share that would improve this article?
Email your photos

More for You

See All

Written by Joan Agie

Bachelor of Science specializing in Human Anatomy

Joan Agie picture

Joan AgieBachelor of Science specializing in Human Anatomy

With 3+ years of research and content writing experience across several niches, especially on education, technology, and business topics. Joan holds a Bachelor’s degree in Human Anatomy from the Federal University of Technology, Akure, Nigeria, and has worked as a researcher and writer for organizations across Nigeria, the US, the UK, and Germany. Joan enjoys meditation, watching movies, and learning new languages in her free time.

Read full bio >