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Do Fish Ever Get Thirsty?

Do Fish Ever Get Thirsty?

Water is essential for life. We all need to drink water to survive; we need it to maintain various balances within our bodies, most notably a balance between water and salt.

Fish live and thrive in water. They need to remain under the surface of the water to live. But does living in water mean fish do not need to drink it? Do fish get thirsty?

No, fish do not get thirsty; they are unlikely to seek out and drink water as a conscious response because they live in water. Thirst is commonly defined as a desire or needs to drink water. Fish are unlikely to respond to such a driving force.

Find out more about the types of fish and how they consume water by reading the article below.

How Do Fish Consume Water?

How fish consume water depends on what type of fish we are talking about. There are fish that live in freshwater, fish that live in saltwater, and fish that dwell in the ocean’s saltwater.

Saltwater Fish

When fish live in salt water, the salt concentration in the water is greater than the salt concentration within their bodies. As a result of osmosis, water moves from their bodies to the water around them. 

As a result, they are always at risk of dehydration, which seems odd given that they live in water.

To compensate, the fish must aggressively swallow water through their mouths. They digest the water, producing modest amounts of salty urine and secreting salt via specialized cells in their gills.

Fresh Water Fish

Fish that live in freshwater don’t drink much water at all, at least not in the way that we do. They don’t take much water in through their mouths, if they did, they would risk over-diluting their blood and unbalancing the salt-water balance within their bodies. 

Freshwater fish have a higher salt concentration in their blood and body tissue than in the water surrounding them. They take small amounts of water into their bodies through their skin and gills and then pass excess water through urine. 

The process that allows the water to pass into their bodies this way is called osmosis.

Do Fish Get Dehydrated?

Fish can experience dehydration, as electrolyte loss can also occur in them. Even though they live in water, this can lead to dehydration. It could happen as a result of kidney failure.

If you keep your fish in an aquarium, you must change the water on a regular basis to prevent it from becoming polluted with waste produced by the fish (which would make them sick).

Fish are widely regarded to be the only living species that can survive in water without becoming dehydrated. However, even when they have access to water, fish can lose electrolytes through their gills and skin. Even though fish live in water, this loss might result in dehydration.

How Do Fish Breathe In Water?

Fish take water into their mouth, passing the gills just behind its head on each side. Dissolved oxygen is absorbed from—and carbon dioxide released to—the water, which is then dispelled. 

The gills are fairly large, with thousands of small blood vessels, which maximizes the amount of oxygen extracted.

Though some fish can breathe on land taking oxygen from the air, most of the fish, when taken out of the water, suffocate and die. This is because gill arches of fish collapse, when taken out of the water, leaving the blood vessels no longer exposed to oxygen in the air

Excretion In Fish

In fish, the kidney is a vital organ. The kidneys digest the water, nutrients, and salts that the fish absorb. It also controls the quantity of salt in the bloodstream. Fish are born with two kidneys, one on each side. The kidneys are responsible for all osmoregulation, whether in freshwater or saltwater.

The kidneys of fish are divided into two types: the head kidney and the posterior kidney. The head kidney is in charge of filtering wastes from the water that goes through the gills. The posterior kidney filters waste and excretes it through urine.

Here’s something for you to watch as you read ahead: 

Difference Between Osmoconformers & Osmoregulators

Osmoregulaters and osmoconformers are two types of fish that maintain bodily fluids in different ways.

Osmoregulators maintain steady body levels unrelated to the external environment, whereas osmoconformers match the body to the external environment. Osmoregulators are fish that can survive in a variety of environments.

Osmoconformers are marine animals that adapt to changes in their external environment by changing their internal circumstances. Freshwater fish can be osmoregulatorers or Osmoconformers.

Osmoregulators constantly regulate their body in order to maintain a constant internal environment. Osmoconformers on the other hand have the advantage of being able to survive in a wide range of environments.

Some fish like salmon move from saltwater to freshwater and back. These fish are able to adapt to both ways depending on where they are.

Do Salmons Get Thirsty?

Some fish can live in both fresh and saltwater; salmon, for example, passes from fresh water to salty water and then back again, at different stages of their life cycle. Their bodies switch from one process to another to cope with the changes in salt concentration. 

When salmon move from freshwater to saltwater, they start to drink a lot of water and reduce the amount of urine they excrete. Specialized cells within their gills pump salt out of their bodies. All these changes happen over the course of several days, usually while the fish is in the intertidal zone.


Many people believe that fish are thirsty, yet they are not. This is due to their highly efficient system for controlling the amount of water in their bodies at all times. The most crucial component here is osmoregulation, allowing fish to thrive in salt and freshwater settings.