Koi Staying in One Spot

koi fish staying in one spot while other koi eat

Causes & Solutions ~ Pond Fish Not Moving

Koi fish are energetic fish that usually explore all pond areas once they are comfortable with their surroundings. They are eager to get to know each other and swim freely. They will rarely stay at one place or on the bottom for more than a minute.

When a person is nearby, healthy koi move quickly and with alertness. You should take immediate action if you see a koi that is not moving or is showing erratic swimming behavior, especially in the spring and summer. You should be concerned if your koi is staying in one spot during mealtimes. Usually, only serious problems prevent koi from eating.

If you notice a pond fish not moving along with unusual symptoms, it is essential to check that it is still breathing. Likely, it is still living. However, you will need to provide immediate medical attention or medication for its recovery. Stress is the leading cause of koi staying at the bottom of a pond. However, it can also be caused by other factors. Here are some possible causes of koi immobility, which can be challenging to spot. While many of these can be corrected without professional assistance, others require expert guidance and advice.

Potential Causes of Koi Staying at the Bottom of Pond

Poor Water Quality

Poor water quality is one of the leading causes of koi staying at the bottom of a pond and leading to a heightened risk of koi not moving. You may notice unusual behavior in multiple koi. However, only one or a few may show symptoms of illness. Fish with impaired immunity will not survive in poor water conditions. They will need medication or special treatment.

Check your water parameters immediately you spot a sick fish. Check that the pH, ammonia, nitrite, chlorine, and pH levels are within a normal range. Any higher than zero for ammonia or nitrite can signify that your filter is not working correctly. Ammonia poisoning can cause fish to seek refuge at the bottom of the pond. If you look closely at their fins, these fish may show streaks of blood, erosion, or other signs of distress.

The pH level of your pond should be between 7.0 and 8.0. Metal toxicity (heavy metallics dissolve in acidic waters), hypoxia, or alkalosis can lead to health problems. All of these can cause immobility and lethargy. You should also check the water hardness levels. Your pond water’s GH (general hardness) should not exceed 10@dH. The KH (carbonate hardness) should not exceed 6@dH.

Your pond might need to have a significant water change if any parameters are out of the normal range. But, be careful not to use city water with chlorine without dechlorinating it first.

You also may need to add biological filters or more pond plants.

Poor Oxygen Levels

Koi ponds should have dissolved oxygen levels of 6 ppm (6 mg/L). Any lower than this level can lead to koi Hypoxia or an increase in harmful nutrients. Poor oxygenation can cause water quality to deteriorate over time. These can lead to a combination effect that can make it challenging to diagnose koi disease. It makes sense to look for signs and symptoms of hypoxia to ensure it doesn’t worsen if it is indeed the problem. Symptoms include slowness, lack of appetite and gathering near water sources (such as an air bubbler), and a koi breathing at the surface along with pale-colored gills.

DO levels lower than six ppm can cause a decrease in tissue repair and a reduction in koi immunity. It can also increase the risk of parasites and bacteria spreading, severely impacting fish survival and growth. Regularly measuring your pond’s DO is essential as oxygen levels can fluctuate due to increased fish density, salinity, and changes in water/ambient temperature outside.

You should use a reliable DO tester or test kit and test your pond’s water column for DO levels. If values are insufficient, you might need more aerators or oxygenating aquatic plants. You should check your air pumps for wear and keep spare parts in stock to prevent any drops in DO.

Pump failures do happen along with power outages- and even short periods without oxygen can cause severe illness to your koi.

Disease & Parasites

As with all living things, koi afflicted by diseases and parasites will have a more challenging time moving around. Parasites can cause infections and disease in fish, so if koi stay in one spot, their swimming organs may be compromised. To prevent irreversible damage, lookout for early signs of parasitism.

  • Mucus production can cause cloudy skin
  • Lethargy, listlessness, or immobility (commonly displayed by koi fish sitting at the bottom of the pond)
  • Redness of the skin or fins
  • Pale gills
  • Cloudy eyes
  • Distress

Many diseases and parasites can cause this. You will likely need to remove the affected koi from the pond and inspect any exposed areas for signs of infection. A mucus sample or skin scrape may be required to diagnose microscopic microbes. Many parasites of fish, including Trichodina or Ichthyophthirius multfilis, may not be visible to the naked eye. They can be hidden while your koi become weaker.

Swimbladder disorder is another disease that can cause your koi to struggle and not swim freely. It can be either permanent or temporary and requires close monitoring. The brief form of the disorder can be treated with frozen or cooked green peas. This should reduce the pressure in your fish’s bladder and take only a few hours. Permanent forms will require professional treatment, which may include surgery.


Koi can panic when they are scared and frantically swim to hide. The koi can inadvertently hurt themselves and other fish. They can become exhausted.

After the source of fear is eliminated, the koi may not move at the bottom of the pond for a while but should soon be able to swim normally again. To prevent injury, provide more shelter and safe hiding places for your koi. These shelters can be either herbaceous floating plants or artificial covers with smooth edges that sit at the bottom of your pond.

Water changes, relocations from one water body to another, and mating/spawning are all possible causes of exhaustion. Koi can become very tired when adjusting to new environments and recovering from high-energy activities. This is especially true if the water parameters are not ideal. To aid in recovery, you can add additives to your pond water to remove heavy metals and ammonia. This is an excellent option for fish who need to adapt to new waters, especially with few healthy pond bacteria.


Koi are poikilothermic fish that rely on water temperatures for many internal bodily functions. As temperatures drop during winter, koi metabolism slows down. This can affect their energy levels and swimming behavior.

Your koi will gravitate to the bottom of your water column if the pond is frozen. This is because the temperature there is higher. Sometimes they may appear not to be moving beneath the ice. You’ll notice that they move slowly and can swim short distances if you keep them in your sight for long enough. Which helps keep their joints mobile.


Overcrowded fish ponds can create stressful situations for your koi. High fish densities are associated with higher waste loads, which increases the need for oxygen.

Remember that your koi are likely to breed, which will increase your fish density further. Overcrowding can lead to aggression and competition for food. You might find less vigorous koi starved or subject to nutrient-poor pond bottom scraps.

Frightening and disease transmission may also increase if there is frequent contact between fish. Parasites can be passed more quickly from one fish to the next, resulting in a whole pond full of sick fish.

 Avoid overstocking your pond to protect your fish and yourself from stress. In this case, as with most things, more is not always better.


As with all living things, koi can become weaker and more tired as they age. Your koi’s immunity can become more vulnerable or less resilient as organs start to fail.

Old koi fish can no longer tolerate water fluctuations and recover as well as they used to. When young koi are introduced to a pond system, some of the older koi may experience ” Old pond syndrome. This is when their bodies can’t cope with an influx of new bacteria. Although koi are said to live up to dozens of years, their longevity is greatly dependent upon the skill of their pond keeper.

If you have spotted a koi who refuses to move or doesn’t want to eat, it is time to evaluate your pond. Also, check if other fish behave similarly or show signs of stress.

Make sure you go through your mental list of parameters mentioned above and test each one. You can respond to abnormal levels of nutrients, pH or water hardness, or chlor by performing water changing or using pond additives to restore values to average. And consider adding an aerator in your pond if your dissolved oxygen levels have suddenly dropped.

What if Your Koi is Sick?

If your fish show signs of stress but all other parameters are inline, you should consider isolating them.

Take out any weak or dead fish and place the healthy ones in a quarantine tank. If the fish are infected with parasites or infectious diseases, this will prevent them from transmitting it to the other koi. You may consult a koi veterinarian to determine the best treatment. If you cannot consult a veterinarian, take the time to scrutinize your koi for parasites. You should gently check your fish’s tail, mouth, fins, and scales for any unusual behavior.

If you detect parasites, use an anti-parasitic and broad-spectrum antibiotic made for ornamental fish. But be sure to read the label carefully and not just guess how much you add to your quarantine tanks. If the illness is reversible, give your fish some extra time to recover before transferring back into the pond. 

Last Updated on March 9, 2023 by Davin