Do Fish Pee ? Fish in aquarium

Do Fish Pee


Do fish pee? If not, then how do their body’s wastages get excreted? And if they do excrete, then how do they pee? Do they pee wherever in the water, or have they chosen a separate toilet area in their habitat like us? Well, there are a bunch of such questions that often start crowding our thoughts. But what is the actual truth behind it?


Well, the answer to do fish pee is YES! Fish pee to eliminate wastes from their body and keep their systems functional. The water absorbed through osmosis is processed as urine through their kidney. Some fishes pee through their gills or skin; others use any of their body pores at the rear end.


Do fish pee?


Well, the question, do fish pee is a mystery, as most of us might not have never seen them peeing the way we do. Even if they pee, it is not much clearly visible, as we can barely understand what they are doing underwater. These cuties have many mysteries hidden in their body, which makes us more curious about them.

However, the shortest and simplest answer to the query, do fish pee, is yes. Like most other living beings, fishes produce some waste in their bodies due to their metabolic processes. Hence, peeing is one way for them to get rid of wastes, which is commonly known as excretion.

Though you may not catch them peeing prominently, fish do urinate, which gets mixed in the water they are living in.


What do fish pee with?


Fish use their kidneys to produce urine in their body. However, the way to excrete urine out of their body is entirely dependent on their anatomy.

While most fish use their gills for peeing, some pee through their urinary pores.

The fishes whose kidneys are not very active or functional tend to urinate through gills. On the contrary, urinary pores are present in those fishes that eliminate urine after proper filtration through kidneys.

Besides, many fishes get rid of their urine through the tiny openings situated at their rear end. Also, some fish prefer to pee through their skin.


How much do fish urinate?


As you already know, fishes do pee to excrete wastes from their body. But now the question is, how often do they urinate? Well, how much a fish will pee is entirely dependent on the environment they are living in. Also, the adaptations a fish has undergone for its survival impact its peeing behavior.

Usually, freshwater fish and marine fish have some differences in their peeing behavior. You will see freshwater fish tend to pee more than saltwater fish. Wondering, why? Well, that’s because of the difference in the salinity level of their outside environment and inside their body.

Fishes tend to have thin skin around the places of their gills. Hence, water continuously flows in or out of them through diffusion and osmosis.

Now, in the case of freshwater fishes, their bodily fluids and blood are more saline than the water in their surroundings. Hence, they constantly keep gaining water from their habitat.

The kidney of freshwater fishes prevents excessive solute loss as they contain more salt in their blood. Water gets diffused into the fish’s body through the osmosis process, which causes a large amount of water to accumulate in them.

After that, their kidney amplifies the amount of water passing through their urine. Hence, freshwater fish tend to excrete dilute urine more frequently.

On the contrary, the body of marine fishes is less saline. Their kidney functionalities are almost opposite to that of freshwater fish. As the water in their surroundings is highly concentrated with salt, water gets sucked out of their body constantly.

Hence, to counteract this water deprivation, saltwater fishes drink lots of water. Continuous drinking replaces the water lost from their body. However, the salts they intake get filtered out through their kidneys. Hence, they produce concentrated urine in lesser amounts.

So, even though freshwater fishes do not drink water like saltwater fishes, the former feel the urge to pee more often due to their higher salinity level in the body.


Do fish pee in the water?


Yes, fish tend to pee in the water they dwell in. However, the urinating behavior of fish is not as frequent as other animals or humans.

They have two little kidneys and a bladder, which helps them to get rid of the unwanted liquid out of their body.


Do saltwater fish pee?


Though the peeing amount of saltwater fish is lesser than freshwater fish, they do pee. Usually, saltwater or marine fish have lesser salt content in their body compared to the surrounding water.

So, the highly concentrated brackish water sucks out the less saline water out of their body. Hence, saltwater fish tend to lose water from their body constantly due to this osmosis process. Also, their kidneys function in the opposite way than freshwater fishes.

Thus, saltwater fish compensate for this water loss by drinking adequate water, maintaining proper fluid balance in their body. Hence, the production of urine in saltwater fishes is much lesser in quantity.

On the other hand, their kidneys help them filter the excessive amount of salt to prevent the build-up of harmful substances in their body. Thus, the urine they produce is highly concentrated and saline.


Do betta fish pee?


Betta fish usually come with a bladder in their bodies, which helps them perform the necessary peeing process.

Besides, betta fish also possess a small urethra. It is a tiny opening through which urine flows out of their bladder.

Usually, betta fish pee through their gills, as they have a tiny kidney. Thus, if your fish is not peeing through its gills, then it must be having a poor immune system.


Do jellyfish pee?


Though this sea creature is named a fish, it does not pee, similar to other common types of fishes. In fact, the idea about whether jellyfish pee or not is not at all clear.

Jellyfishes are known to participate in the osmosis process for keeping themselves hydrated. Also, they extract excessive amounts of salt to maintain optimum salinity levels in their body.


Do fish pee and poop?


To maintain a healthy balance of their body and remove waste matters out of their system, fishes pee, and poop. Both marine and freshwater fish excrete poop and pee to get rid of waste matter.

Similar to humans, even fish have two kidneys. But the shape and size of the kidney vary from one fish to another. And based on it, their peeing behavior varies.

However, fishes do not pee many a time. Instead, they do it mostly once a day. It takes a long time for their kidneys to complete the process. Hence, their excretion rate is very low.

Also, it takes a much longer time for a fish to poop. Their digestion system gets jammed up as they pick food. It takes several days for them to complete the digestion of the entire complex food. Thus, they seldom poop.


How do fish pee and poop?


Unlike others, fish pee and poop less frequently. Usually, their kidneys function relatively slower than any other species. Hence, it takes much time for urine generation in their body.

The fish pees when it feels the urge to do so. It is seen that most fishes pee once a day through their urethra tract.

Similarly, fish tend to poop as and when they feel the urge to eliminate the waste matter out of their body. Their pooping is much dependent on their bowel movement and the quantity and quality of food they eat regularly.


Do coral reefs absorb fish pee?


Yes, coral reefs do absorb fish pee.

As a fish urinates on coral reefs, the corals tend to wave their tentacles and absorb the necessary nutrients from their pee.


Are fish attracted to urine?


There is a well-known myth that fishes are much attracted to urine. Well, this myth was famous by the name candiru attack. Such tales were usually heard back in the 19th and early 20th centuries.

The myth says that a fish, named candiru, gets attracted by human urine in the water. So, whenever a person, usually men, urinates in the water, the fish tend to swim up into the urethra of the individual.

However, it is hard to find whether such incidents were even true or not. As per medical literature, there are only a few reports of candiru attacks.


Does fish oil make you pee more?


Consuming fish oil regularly does not affect your amount of urination. However, it does have some side effects on your peeing.

Well, the most significant adverse effect of fish oil supplements is diarrhea.

However, the enteric-coated forms of fish oil are used to dissolve distal in your stomach, which helps reduce such potential gastrointestinal problems. Besides, taking fish oil supplements can cause a fishy smell in your urine.


Should you pee on a jellyfish sting?


Though there is a widely popular myth that peeing on a jellyfish sting can give you relief, there is no truth behind it.

There is no factual evidence that peeing on a jellyfish sting can help you feel better in any way. In fact, various studies have claimed that there is no logic behind it.

But then why did this myth evolve? One of the possible reasons for the emergence of this myth may be the presence of compounds like urea and ammonia in urine.

It is evidenced that when these two elements are used separately, they tend to produce some soothing effect for certain stings. But human urine is so dilute that it nullifies the effectiveness of ammonia and urea, rendering no help in soothing jellyfish stings.




Thus, peeing and pooping are some of the common bodily functions observed in any organism, including fish. As fishes absorb or drink water through their gills or mouth, the water passes through their kidneys, which extracts out the waste matter from their body in the form of urine.

Hence, the answer to your question, do fish pee, is a definite yes. It is a much necessary activity that fishes perform to stay healthy and well-functioning.