Can fish drown in Water?

Can fish drown in Water

Aquatic animals pertain to animals that live predominantly in different water forms, such as seas, oceans, rivers, lakes, ponds, etc.

Examples of aquatic animals include fish, jellyfish, sharks, whales, octopuses, barnacles, sea otters, crocodiles, crabs, dolphins, eels, rays, mussels, and so on.

Aquatic animals may breathe air or extract oxygen from the water through specialized organs called gills, or directly through the skin.

Natural environments and the animals that live in them can be categorized as aquatic (water) or terrestrial (land).

So, is a fish considered an animal? Yes? Or no?

Classification of fishes

According to science, fish are classed as animals. Fish belong to one of the six general animal groups which are: mammals, birds, reptiles, amphibians, fish and invertebrates.

While the flesh of fish might not be considered as meat, fish are animals that have brains and can feel pain.

There are lots of different kinds of fish, which range in size from the dwarf minnow at around 1 cm to the whale shark which can reach up to 10 meters in length.

All fish live in water and have gills, scales, and fins.

Fish are unique in that they have a combination of gills and fins and that they live only in the water.

While some invertebrates and amphibians have gills, some mammals and amphibians have fins and lots of animals live in water, only fish have the combination of all three attributes.

Fish swim by flexing their bodies and tail back and forth.

Fish stretch or expand their muscles on one side of their body while relaxing the muscles on the other side.

This motion moves them forward through the water. Fish use their back fin, called the caudal fin, to help push them through the water.

Most fish breathe when water moves across their gills. But if the gills are damaged or water cannot move across them, the fish can suffocate.

They don’t technically drown, because they don’t inhale the water, but they do die from a lack of oxygen.

Your average fish can breathe perfectly fine, however, both in motion and at rest, so long as the water is oxygenated sufficiently.

They will not die if they stop swimming. Simply being in oxygenated water is enough for fish to breathe and survive.

Do fish die if they stop swimming? 

Sharks can die if they are unable to swim. This is possibly where the myth that a fish can die if it stops swimming came from.

Buccal pumping

You see, sharks must swim to force water past their gills. 

They also use what is called “buccal pumping,” which allows them to use muscles in their throat to force water past their gills. 

However, not all sharks are capable of this technique and will die when they stop swimming.

Drown and suffocate are often used interchangeably when they really have two different meanings.

To drown means to die from a lack of oxygen through inhaling water, typically due to being submerged in water.

To suffocate means to die from lack of air or being unable to breathe.

While they are similar emergencies that both relate to not having enough air, they are two completely different causes of death.

This is why a fish technically can’t drown in water, but they can suffocate.

Can Fish Actually Drown in Water?

No, a fish cannot technically drown, but it can die in water due to suffocation. There are many reasons that this can happen.

Reason #1: Damaged Gills

Gills to a fish are like lungs to a human. We need them if we want to breathe, and damage can make breathing more difficult.

A fish can suffocate if it has damaged gills because the gills won’t allow enough oxygen to enter the body and replace the carbon dioxide.

Reason #2: Live Plants Taking Up Oxygen

This is related mostly to aquarium fish. If you have many live plants in your aquarium, you may be inadvertently suffocating your fish.

Live plants can take up oxygen and reduce the amount of oxygen found in the aquarium, so you’ll need to find ways to add oxygen back into the aquarium to protect the fish.

Reason #3: Overcrowding

This is another condition related to aquariums.

If you have too many fish in your fish tank, your fish won’t be able to get the adequate amount of oxygen they each need.

This can cause your fish to suffocate.


  • Can a fish drown? Not technically, but they can suffocate in water.
  • Fish need oxygen levels in their watery home to be two parts per million – or more – to survive. Without it, they suffocate (what some people refer to as drowning).
  • Fish do not have lungs – they have gills and other organs that function as their respiratory system.
  • Fish use their gills to pull the oxygen from the water, which then allows them to breathe.
  • Fish are cold-blooded (only one warm-blooded fish has been discovered) and therefore have a slower metabolism than mammals. This means they need less oxygen than warm-blooded creatures.
  • Fish are more likely to suffocate in aquariums or fish tanks than in their natural habitats.


Next, let’s take a look at the actual process through which a fish can suffocate in water and “drown”.

As we’ve said above, how fish suffocate or “drown” is through the lack of enough oxygen in the water in which the fish lives.

These depleted oxygen levels in the fish tank happen because of a number of reasons.

  • Too many live plants create too much oxygen
  • Overcrowding of the fish tank (too many fish and invertebrates)
  • Too little air movement and flow in the aquarium
  • Limited water surface area

Fish, like humans, dispel carbon dioxide when they breathe.

When they live in an aquarium full of other fish, with a limited water surface area, or in a fish tank that doesn’t allow for air flow, that carbon dioxide can build up and get trapped inside the aquarium.

This means, oxygen is depleted and carbon dioxide becomes a poison to them – just as it does to us.

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