Do fish vomit?

Have you ever wondered if fish can vomit? Maybe you’ve seen your fish do so, or are just curious. Whatever the reason may be, we have the answer for you!

So do fish vomit? Reason? What can I do?

Well, to simply answer the question, yes, fish can vomit for a number of reasons. These include stress and overeating. You can mostly either remove the stressor, make the food more digestible, or in some rare cases, get your fish a treatment. 

Stop overfeeding your fish (Video)

There’s a lot more to it than just that though. We will now dig into the particularities of this topic. If you’re still curious (or concerned for your fish), then read on!

Do fish vomit?

Yes, fish do and can vomit. One might argue that fish can vomit because every living creature does. Interestingly, not all animals can! But fish have been noted to be able to do so. However, they aren’t frequent vomiters and tend to do so very rarely.

When a fish vomits, it can be in a number of ways. They can either vomit out large chunks of food, or they can vomit out already digested food. The difference between the two is very crucial to note, and we will look into it in detail further down in our discussion.

Why do fish vomit?

There are a number of reasons that fish might vomit due to. They can broadly be classified into three distinct categories, which we will explore in detail.

The first of the categories is when fish vomit out large chunks of food. This is when the fish has just put food in the mouth and wants to bring it out again. This can be due to a number of reasons.

For one, the fish might have taken a lot of food in its mouth because it wanted to save for later. It would then let the food out of its mouth and eat it again. The second reason might be because the fish were unable to digest the food in one go. They would then let that food out and take it into their mouth again to chew it and digest it again. The fish use this method to break down the food further so that they are eventually able to digest it.

The second reason that a fish might vomit is because of a stressor being present. When a fish senses a stressor, it would try to swim away. That is a natural environmental response. When the fish wants to swim away quicker, it helps to have the stomach empty. The fish would thus spill out the contents of their stomachs. Some fish, particularly sharks, have been noted to vomit their stomach and organ out as well in a bid to escape!

See also  Platy Not Eating and Staying At the Bottom Of Tank – Reasons?

The third reason that a fish may vomit, would be a disease. These can include dangerous diseases like Hexamita. These diseases are often accompanied by other symptoms and should be particularly quickly treated.

How to recognize what reason made your fish vomit?

Now that we know the reasons for fish vomit, it is important to understand what exactly made your fish vomit. There are a number of hints and cues that we can look at to understand that.

For one, we have to identify what the vomit is. If the fish is vomiting out large chunks of food, then you can rule out diseases. This means that the fish would either only be trying to digest the food, or has a stressor present around it. To further understand which subcategory this behavior would fall in, you would have to decipher the fish behavior.

If a fish vomits some food and immediately eats it again, it means that it is only trying to digest the food, or took too much in its mouth. In that case, we can rule out the stressor. You can note the fish feeding to understand if it’s taking too much food in at once or if it is having trouble digesting.

If a fish is vomiting out large chunks of food and is not eating it again, it is probably caused by a stressor. The fish would also display other signs of stress and fear, like sticking to one corner and not moving.

If the fish is vomiting already digested food, it could be caused by pathogens or by a stressor. If a pathogen is present, the fish would typically also display other symptoms. These can include swimming backward, as well as a hole in the head. These can quickly let you recognize the cause behind your fish vomiting. It is also very important to ensure that the water your fish are in is clean to ensure that they don’t get infected. If they’re not displaying any other symptoms, we can assume a stressor is causing the behavior.

What can I do about my fish vomiting?

So now we know why fish vomit. The next question is obvious: what do we do about the vomiting fish.

See also  Why Do My Ghost Shrimp Keep Dying?

If the fish is vomiting because it is taking too much food in its mouth, it feels that there is a competition for food. You may want to consider providing more food to your fish.

If the fish is vomiting to redigest food, the diet might not be adequate for the fish. You can either cut up the food into smaller pieces to help the fish out, or you can change the feed that you are using and opt for something more suited to your fish.

If the fish are responding to a stressor when vomiting, you should remove the stressor from the environment. You can identify what the fish is swimming away from. It is likely to be something new added to the tank, which the fish has not grown accustomed to yet. The fish should grow accustomed to it soon, if it doesn’t, you should consider removing the new accessory.

If you identify the fish as getting sick, you should perform regular cleanups of your water tank. You do not want the tank to have high levels of contamination, as it can harm the fish. If the disease is something particularly bad, like Hexamita, you should consider visiting a vet to ensure that your fish gets treatment and is safe. If the disease is contagious, you should isolate the vomiting fish from the rest of the tank mates.


Having dug into the particularities, we know that fish do indeed vomit. Fish tend to be very attacking when it comes to food, and vomiting is not abnormal behavior. You can typically ignore the vomit of a fish unless it comes out in an entirely fluid state.

With that being said, it is still important to ensure that you keep a close watch on a vomiting fish. It is important to remove any stressor for the fish immediately and to ensure that your fish is not infected. So just keep a close eye on the fish, and ensure that the vomit is simply due to binge-eating. And if it’s not due to that, take prompt action and save your beloved fish some pain!

Photo of author

Nadine Oraby

My name is Nadine; I am a passionate writer and a pet lover. People usually call me by the nickname “Joy” because they think that I am a positive and joyful person who is a child at heart. My love for animals triggered me to create this blog. Articles are written by vets, pet experts, and me. Thanks for visiting. Your friend, Nadine!

Leave a Comment