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Home > Goldfish > Can Goldfish Drown? Vet-Reviewed Science & Info!

Can Goldfish Drown? Vet-Reviewed Science & Info!

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Goldfish are aquatic creatures that are not capable of drowning. However, certain diseases can affect your goldfish which may make it appear as if your goldfish is struggling to breathe underwater.

It is fascinating to observe goldfish in their vastly different habitat, and interesting to learn how they breathe and survive underwater. Goldfish have adapted to life underwater and rely on a pair of gills for their dissolved oxygen intake.

There is a possibility that goldfish can struggle to breathe underwater for various reasons, which can make it appear as if your goldfish is drowning and struggling to take in air. This article will provide you with all the answers you need as to how goldfish can drown underwater and what the correct term and factors that can lead to this occurrence are.


Is It Possible for Goldfish To Drown?

In simple terms, a goldfish can’t drown. However, goldfish can suffocate underwater. Goldfish do not have lungs which are found in mammals and used to breathe in oxygen. Instead, goldfish have gills and breathe dissolved oxygen in the water.

Many fish keepers make the understandable mistake of using the word “drowning” when their goldfish is gasping for oxygen because it is comparable to how a human would not be able to breathe underwater. More accurately, suffocating would be the correct term to use.

This is because drowning refers to the inability to breathe oxygen underwater where water is entering the lungs and making it impossible for the lungs to function properly, whereas suffocating occurs when a goldfish is unable to derive oxygen from water using their gills.

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Sick goldfish lying in the bottom
Image By: mrk3PHOTO, Shutterstock

How Do Goldfish Breathe Underwater?

The key to understanding how goldfish breathe underwater without drowning is to learn about how their body functions to take in oxygen and release carbon dioxide underwater.

The bodies of goldfish maintain various organs that require oxygen to function properly, which makes it important for goldfish to have the right bodily anatomy to breathe efficiently underwater. The gills of a goldfish are composed of a group of epithelium cells which enables the goldfish to deliver oxygenated blood by their arteries to their organs.

Water is taken in through the goldfish’s gills and moves across the membrane of the epithelium which then allows the oxygen to be absorbed into their bloodstream. The carbon dioxide that is produced by a process known as cell respiration is then released from their bodies (however, it is worth noting that unlike mammals, the primary product of fish metabolism is ammonia, not just carbon dioxide).

Gills are located at the side of a goldfish’s head and a goldfish will open and close its mouth to move the gill flaps. By lowering the bottom of their mouth, the gill will widen and water with dissolved oxygen will be taken in. When your goldfish closes their mouth, the water with oxygen is then trapped inside and taken in through their bodies. After the dissolved oxygen has entered the gills and pulled out, excess water then leaves the goldfish’s body through an opening called the operculum.

A mostly white lionchu goldfish looking right into the camera
Image By: Sardo Michael, Shutterstock

How Do Goldfish Suffocate Underwater?

A goldfish will suffocate in water when there is no dissolved oxygen left to be taken into their gills.

This can occur for several reasons:
  • Illness: There are some illnesses such as fungal and bacterial infections that can cause the gills or mouth of a goldfish to rot or become covered in a type of fungal growth. This prevents the goldfish from being able to properly open and close their gills which causes them to lose oxygen over time—eventually leading to suffocation.
  • A Build-Up Of Ammonia & Carbon Dioxide: If you keep your goldfish in a small-sized aquarium (such as a bowl) or too many goldfish in a tank, it can cause carbon dioxide and ammonia to build up which can harm the fish. This is because a small body of water with too many goldfish can cause the oxygen levels to deplete while the amount of carbon dioxide and ammonia increases.
  • Gill Damage: Goldfish can sustain an injury to their gills through rough tankmates that might nip at your goldfish’s gills, if they have scraped it against a sharp object in the tank, or if the water quality is poor and burns the gills (especially in cases with high ammonia). This can make it difficult for your goldfish to use their gills properly.
  • Poor Aeration: You must have an aeration system in your goldfish’s tank so that the surface of the water is constantly moving to encourage gaseous exchange so that more oxygen can get dissolved in the water. Aeration systems include bubblers, air stones, or spray bars attached to a filter.
  • Warm Water: The warmer the water, the less dissolved oxygen will be present in the water. Goldfish seem to prefer cooler water over heated water, so if you notice that your goldfish’s water is becoming too warm, they may begin to gasp at the surface where the level of oxygen is the highest.



Although goldfish cannot drown, they can suffocate underwater. This makes it important to ensure that you keep your goldfish in an appropriate setup with the right water conditions and aeration systems. Treating your goldfish for any injuries and diseases can also help to keep their gills functioning properly.

Featured Image Credit: Dien, Shutterstock

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