Koi can be a tricky species to keep and although more and more people are starting to set up their own koi ponds, we have noticed more and more people reaching out with a range of different questions about caring for their pet koi.
We already have articles online going over why koi fish may not be eating as well as why a koi fish may lose its scales after seeing people asking questions about it.
More recently though, we have noticed a number of people reaching out and asking questions about why their koi fish is laying on its side so much.
After seeing so many people asking questions about their koi fish laying on its side, many of these people worried about the potential health problems in their fish, we decided to publish this article going over the topic.
We hope that we will not only be able to answer any questions that you may have but also help you treat any potential problems that are causing your koi fish to lay on its side quickly to help the fish return to full health quickly.
Is It Normal For A Koi Fish To Lay On Its Side?
It is not normal for a koi fish to lay on its side and if you have noticed that your koi fish has been laying on its side more frequently, it is important to take a closer look at your fish and determine the potential cause of this new behavior.
Depending on your exact setup, your koi fish my lay on its side temporarily but for the most part, this is not a normal behavior and is almost always a sign of a potentially serious problem in the fish that needs you to work on fixing the problem as soon as possible.
What Causes A Koi Fish To Lay On Its Side?
There are a number of different potential health problems which could be causing your koi to lay on its side but we will go over some of the most common causes below.
Swim Bladder Disease
One of the most common reasons why a koi fish may start to lay on its side is because of a swim bladder infection.
A swim bladder infection is a relatively common health problem in koi and other fish species and can be caused by a number of different things such as bacterial infections, changes in water temperature or quality, or even by the fish ingesting something that it should not have.
If you believe that your koi fish may be suffering from a swim bladder infection, you should take a closer look at the fish and see if you can notice any other potential symptoms such as:
- The fish struggling to stay upright.
- The fish having a bloated appearance.
- The fish being less active than usual.
If you notice one or more of these other symptoms in addition to your koi fish laying on its side, it is very likely that the fish has a swim bladder infection and you will need to take action to treat the infection as soon as possible.

Injury
Injury is another reason that your koi may be laying on its side and is a problem that you will need to be on the lookout for if you have other fish in the pond as well.
If your koi has been injured, it may start to lay on its side as a result of the pain that it is feeling and this is something that you need to take action on quickly.
Physical injuries can happen in a number of different ways such as the fish being attacked by another fish or even by you or another person handling the fish roughly.
If you believe that your koi has been injured, you should take a closer look at the fish and see if you can notice any other potential symptoms such as:
- The fish struggling to swim.
- The fish having red or swollen fins.
- The fish appearing to be in pain.
- The fish having open wounds on it.
- The fish having rips in its fins or tail.
If you notice one or more of these other symptoms in addition to your koi fish laying on its side, it is very likely that the fish has been injured and you will need to take action to treat the injury as soon as possible.
Disease
There are a number of different diseases which could be causing your koi to lay on its side and this is something that you need to be on the lookout for if you notice any other potential symptoms in your fish.
Some of the most common diseases which could be causing your koi to lay on its side include:
- Bacterial infections.
- Viral infections.
- Fungal infections.
- Parasitic infections.
If you believe that your koi fish may be suffering from a disease, you should take a closer look at the fish and see if you can notice any other potential symptoms such as:
- The fish having cloudy eyes.
- The fish having visible parasites or fungus growing on it.
- The fish appearing to be in pain.
- The fish having a loss of appetite.
- The fish swimming strangely.
- The fish losing its normal colors and turning pale.
- The fish bloating up due to internal parasites.
If you notice one or more of these other symptoms in addition to your koi fish laying on its side, it is very likely that the fish has a disease and you will need to take action to treat the disease as soon as possible as they can quickly get out of control.
Thankfully, there are a number of quick, easy, and cheap treatments on the market that you are able to use to help your koi fish get over these various diseases and the majority of local fish stores will stock them as standard and be able to offer more specific advice on the issue.
Water Quality
One of the most common reasons that koi fish lay on their sides is due to poor water quality and this is something that you need to be on the lookout for if you have other fish in the pond as well.
If your koi fish are laying on their sides, it is very likely that the water quality in the pond is not up to the required standards and this is something that you need to take action on quickly.
There are a number of different factors which can impact the water quality in your pond such as:
- The number of fish in the pond.
- The type of fish in the pond.
- The size of the pond.
- The amount of vegetation in the pond.
- The amount of debris in the pond.
- The pH level of the water.
- The temperature of the water.
- The ammonia, nitrates, and nitrites in the pond.
If you believe that the water quality in your pond is poor, you should take a closer look at the water and see if you can notice any other potential problems such as:
- The water being cloudy.
- The water smelling bad.
- The fish appearing to be in distress.
- The fish losing their normal colors and turning pale.
You can use a cheap water test kit on your pond water to get an accurate reating of any of the potential problems that are in the pond if you want to get a more accurate reading of any potential problems in your aquarium with your water parameters.
Thankfully, the majority of problems with water parameters are quick and easy to fix and in many cases, a simple 15%-25% water change should be able to fix the issue.
In more serious cases, you may have to apply chemical treatments to your pond to help get the parameters back in line.
Once your water parameters have been corrected and the overall quality of your pond water improved, your koi should start to act normall again and stop laying on their side.
Do Koi Hibernate On Their Side?
Koi fish do not hibernate on their side so if you do see your koi laying on its side then there is a high chance of there being a potentially serious problem with your fish.
During the winter months, koi fish will become less active and will often spend a lot of their time at the bottom of the pond where the water is colder.
We have an article going over keeping koi in a 55 gallon tank during the winter months that may be helpful to you if you do live in an area that is too cold to keep your koi in your pond during the winter.
They will not, however, lay on their side as they enter into a state of dormancy and this is something that you should be aware of if you see your koi laying on its side.