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Do Fishes Drink Water: A Comprehensive Answer

Do fishes drink water like every other living thing? Oh yes, they do, no living thing can exist without water.

Most fish need water as oxygen supply to breathe. The fish drink water, for oxygen supply. Read about countercurrent mechanism, which will explain about how oxygen is obtained from water and diffused into blood.

Water makes up a large part of our bodies, as it does with all animals. In people, this figure is around the 60%-70% mark. Now luckily we are not walking puddles, and the majority of this fluid is contained in and around our cells.

It allows all our biological processes to function, giving them a medium to work in. However, we also lose water regularly, via sweat, urine and breathing.

In the case of fishes, they don’t actually drink water, down through the mouth. But obviously they need water like all living things to need to live.

They generally absorb it through a process called osmosis, same way hormones and nutrients are absorbed into our blood.

Osmosis is the flow of water across membranes from areas of low concentration of dissolved things (solutes) to areas of high concentration. It serves to equalize the concentrations in the two areas.

In the case of freshwater fish, their blood and bodily fluids are much saltier than the water they swim in, so water will flow in through their gills. The opposite is true for saltwater fish.

As well as getting water through osmosis, saltwater fish need to purposefully drink water in order to get enough into their systems.

Where their freshwater counterparts direct all of the water that comes into their mouths out through their gills, saltwater fish direct some into their digestive tract.

But fishes’ bodies, just like ours, need a certain concentration of salt to function best. They can’t just allow the water to diffuse freely through their gills; the saltwater fish would shrivel up and the freshwater fish would explode!

To stop the exploding fish phenomenon, their gills have special cells that selectively pump salt in, or out of their blood.

In freshwater fish, the cells constantly pump salt in, and in saltwater fish, they constantly pump salt out. Saltwater fishes’ kidneys also help to filter out some of their salt.

Depending on where they live, fish either drink a lot or pee a lot. In the sea, a fish’s body is less salty than its surroundings, so it loses water across its skin and through its gills via osmosis.

To stop themselves dehydrating, marine fish drink masses of seawater and produce a trickle of concentrated urine.

When migrating fish like trout and salmon move into rivers and lakes, they face the opposite problem and risk absorbing too much water until eventually, their cells begin to swell and burst. To avoid this, they switch from being heavy drinkers to plentiful urinators.

How Do Fish Drink Water

Check it out on the YouTube video attach below or continue reading after the video to find out.

Fish can’t simply take water in by swimming around in it. The water cannot penetrate through their scales, the only way it can enter is via the gills or mouth opening.

Once taken in, the water is taken up by the capillaries and then it is able to move into the rest of the body. Of course, the fish can’t keep continuously taking on water, there isn’t enough room!

To counteract this, freshwater fish have to urinate a lot. The kidneys work overtime to flush this excess water from their system. As freshwater fish are passively taking in water through the gills in large amounts, they, therefore, have no need to drink.

In saltwater fish, the situation is reversed. Now drinking salt water is known to increase dehydration in people, as the salt is taken into the stomach actually removes water from the bloodstream.

In fish, the water from their bodies faces a constant battle with the extreme difference to their salty surroundings.

There is constant pressure to move out through the gills, and the only way they can deal with this is by drinking in the salty seawater through their mouths to rectify this balance.

This then leaves them with too much salt in their bodies. To rectify this and expel the unwanted excess salt, they then produce highly concentrated urine that contains high amounts of salt and low amounts of water.

This is in direct comparison to freshwater fish who produce large amounts of diluted urine. Once again, the kidneys have to work overtime to achieve this!


Do Fishes Drink Water; The short answer is yes, they do. But it depends on the kind of fish you are talking about. Freshwater fish do not technically drink water, as it could lead to their blood getting too diluted. Saltwater fish, on the other hand, do drink a lot of water to keep themselves hydrated.

Water is essential for life, and that fact is undisputed. For fish living in water, the need to drink is regulated by passive biological processes that vary depending on whether they live in fresh or salty water; and to a certain extent, their species.

On the whole, however, freshwater fish do not need to drink while their saltwater cousins have to spend all of their lives gulping it down!

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