Can Fish Drown? | An Intriguing Quest! (How to Prevent?)

Fishes are one of the most essential and beautiful aquatic creatures. Just like humans need oxygen to breathe, fishes also need oxygen but in dissolved form to survive. Water contains dissolved oxygen which fishes pump through their gills and absorbs oxygen in it. You must have seen fishes dying in aquariums and rivers and wondered can fish drown?. Well, there is an explanation to this which we have explained in this blog post in simple words so you can understand the science behind it.

can fish drown

There might be a lot of reasons why a fish die but most of them revolve around problems related to lack of oxygen. Even humans cannot survive without a proper oxygen supply and neither do aquatic animals. We have listed down every possible reason why this problem occurs.

Can Fish Drown?

Most people would say yes fishes can drown but technically fish get suffocated and die. There is a fine line of difference between these two words. Drown means “To die because of excess inhalation of water” whereas suffocate means “To die because of lack of oxygen supply in the bloodstream”.

Humans can drown but fishes don’t as they breathe through the dissolved oxygen in the water. To understand this problem you need to first know how a fish converts oxygen dissolved in water. 

How Do Fish Breathe in Water?

Just like humans have lungs to breathe, fishes have gills that extract oxygen from water and allow oxygen into the bloodstream of fish. Fish take in water through their mouth then they create pressure in their mouth due to which water passes through gills and extract oxygen dissolved in water. This process is called Countercurrent exchange.

how do fish breathe


After extracting oxygen from water, then the oxygen is absorbed into the bloodstream and water along with carbon dioxide is pumped out of gills.

It is extremely important that the oxygen level in water must be higher than the oxygen level in the bloodstream of fish for them to breathe. 

Causes of Low Oxygen Level in the Water

There are several reasons which reduce the amount of dissolved oxygen in water, some of them are:

Depth and Temperature

With the increase of surface temperature causing warm water, the dissolved oxygen gets low whereas when the surface temperature is low causing cold water, the dissolved oxygen content gets high. This is the main reason why we must prevent the average temperature of the earth from rising. 


Rivers influence the oxygen levels of sea and ocean water. As rivers get merged into large water bodies it increases the oxygen content that water carries in that area.

Through Atmosphere

Water bodies get oxygen from the atmosphere. The water bodies with constant flow and strong waves will have more oxygen content as compared to still water because of lack of exchange.

These were some of the major reasons which affect the oxygen content of water bodies, there are some more factors like aquatic plants which affect the dissolved oxygen in the water. 

Why Do Fishes Suffocate?

Here are some reasons that cause fish to suffocate:

Damaged Gill

damaged gill

Without proper functioning of gills, a fish cannot extract oxygen from water. The most common reason for a damaged gill is parasites which cause inflammation and irritation in the gill.

Water Conditions

Water bodies with high ammonia content can cause burns and bleeding in gills due to which leads to breathing problems and suffocation in fish.


overcrowded fish tank

This problem usually occurs in fish tanks and aquariums. Too many fishes in a single tank with a limited amount of water can cause a lack of oxygen for every fish.

Aquatic Plants

Too many aquatic plants will release a lot of oxygen and excess oxygen content can also cause problems of suffocation.

Signs of Low Oxygen in the Water

Some changes in fishes which you can notice in fish if the oxygen level is low in the water:

  • Fast gill movement.
  • Reaching to the surface of the water to breathe.
  • Less appetite.
  • Less moving around.


Oxygen is one of the most important factors on which the lives of both humans and animals depend. In this blog post, we have answered one of the most asked questions regarding “Can fish drown?”

If you have a fish tank or aquarium at your home or you are an animal lover then this information will be helpful for you. If you have any questions or suggestions please let us know by commenting down below.

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