Understanding Fish Hydration: Do Fish Ever Get Thirsty?

Do fish ever get thirsty? Do they need to drink water? Such questions are difficult to comprehend and have no accurate answer. The answer to these questions is complex. Although fish live in water, they must consume the same water for normal body functioning. But can fish get thirsty? Dr. Daniel Pauly, principal investigator of the Sea Around Us Project at the University of British Columbia's Institute for the Oceans and Fisheries, provides insight into how fish interact with water, debunking common misconceptions about whether fish get thirsty and how they manage hydration in different environments.

Most of the time, many things occur naturally and usually, but a more profound thought and probing may leave you wondering why or how they happened. Understanding the background of fish and their environment, as well as how their bodies function, can help clarify if they experience thirst.

In this article, we will explore various aspects of fish hydration, including their drinking habits, behaviors related to water consumption, and the differences between freshwater and saltwater fish hydration methods. We will also touch on how fish survive in different environments and how long they can go without clean water.

Do fish get thirsty?

Depending on your understanding, you can answer this question with a yes or no. Fish are amazing animals with some very creative ways of surviving in water, and different species have naturally evolved different solutions.

How often do fish drink water?

Do fish need to drink water? There is no definitive answer since different species have different needs. But generally speaking, most fish only need to drink sparingly. They get much of the moisture they need from the food they eat.

In some cases, however, fish may not get enough moisture from their food and need liquids more often. For example, certain tropical species that live in warmer climates may not be able to find enough moisture in their diet alone, so they drink more often.

However, even in these cases, most fish drink much less than you might expect. They only need to take a few sips daily to be properly hydrated.

Do fish exhibit any specific behaviors related to drinking or water consumption?

Dr. Daniel Pauly, principal investigator of the Sea Around Us Project at the University of British Columbia's Institute for the Oceans and Fisheries, clarified in an interview that fish do not actively drink water like humans do. He explained:

When water enters a fish's mouth, it doesn't drink; it breathes—like us inhaling air. A fish inhales water, and the gills then extract the oxygen out of the water.

You have to imagine that if you live in the water and you get water in your system as a fish, you don't drink it because you are not isolated from the water. The water is inside of you, outside of you, around you, and you don't drink it. It is there. It's like we don't drink air; we breathe it. And the fish breathe water. They don't drink it.

Is it possible for fish to become dehydrated?

Yes, it is possible. That can happen due to several different factors, including:

1. Environmental conditions

One of the main factors that can lead to dehydration is poor environmental conditions. For example, water with a high salt content can dehydrate fish over time. In addition, low oxygen levels or poor water quality can also cause dehydration.

2. Diet

The diet can also impact level of hydration. For example, mainly eating dry food or exclusively fed dry food may cause dehydration. Fish should consume a varied diet that includes wet and dry food.

What are the main differences in how freshwater and saltwater fish handle hydration?

Dr. Pauly explained that the way fish manage water differs drastically between fresh and saltwater species. He said it all comes down to the salt content of the environment:

The big difference between freshwater and seawater is the salt contained in the water. What happens to freshwater fish is that they are more salty than the water around them. The water penetrates their body, and they must eliminate that excess water.

In the sea, it's the opposite. The body of the fish is less salty than the sea. The water is drained out of the body, and they must get it back in.

Key differences in hydration

• Freshwater fish constantly absorb water through their skin and gills because their bodies are saltier than their environment.
• Saltwater fish lose water to their saltier surroundings, which means they must take in water to maintain balance.

How do fish survive in different environments?

Fish are truly unique animals. They have various shapes, sizes, and colors and can survive in different environments. Depending on the type and the environment, they might have to adapt in different ways to survive.

They can do that by changing their diet or growing other body parts. Here is how the fish survives in different bodies of water to prevent dehydration.