Why Are Koi Jumping Out of the Water and Flashing?

If you are a proud koi fish owner, you probably love spending your free time either in front of their garden pond or their indoor tanks. Indeed, these creatures are certainly among the most magnificently colored fish in the entire world, are they bring pure joy to their observers.

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Especially during warmer days when they are fairly active and playful. But have you ever noticed them trying to get out of the water? So, why do koi fish jump and flashing the water?

Not all reasons hiding behind such behavior are harmless, and you may actually have to intervene sometimes. Therefore, understanding this behavior is essential.

Feeding Time

One of the coolest activities one can do when taking care of these amazing fish is to hand feed them. Koi fish are fairly large creatures, and they are quite intelligent and interactive. So, they can certainly quickly learn how to accept tasty meals from their humans. And they will get used to it in no time.

If you are one of those lucky koi keepers who have been hand-feeding their pets for some time now, this may be one of the reasons why you see them jumping when passing by.

Indeed, when they see you, their human feeder, they will obviously become overly happy once they see you approaching. Why? Because it means that it is feeding time! Your fish may be simply jumping out of pure joy.

Just Playing

Playtime is remarkably similar to feeding time and it presents no reason for concerns. Koi fish are not just smart, but they can also feature individualistic personalities and temperaments.

That means that some of your fish may be calmer while others may be slightly aggressive towards their mates. At the same time, some of your koi may have a big passion for exploring while others may be super-playful.

And those that love playing around may perform funny jumps while doing so. And there is nothing you can do about it, other than enjoying your entertaining fish while doing their own thing.

Although jumping activities per se are not harmful for koi fish, they still do present a risk of injury. Some fish may occasionally hurt themselves while fooling around, as they may accidentally jump onto a rock or a harsh decoration item.

Rarely, fish can also mis-calculate their ability and end up on the grass or floor nearby. This may obviously cause their death if not noticed by a human very soon. Therefore, even though your pets are just playing, and it is a perfectly natural behavior, you should still keep an eye on them whenever you get a chance to.

And we know, this will certainly not be a difficult task for you, as observing koi fish while jumping can be utterly amazing.

Poor Water Quality

Sometimes, jumping and flashing behavior is a clear indicator that something wrong is going on with your koi pond (or tank). Since fish do not speak human, it may be difficult sometimes to know the difference between happy jumps and distress jumps.

Luckily, a testing kit should always be somewhere around, and using it frequently is the only certain method of knowing your water quality.

If you suspect of distress among your fish, do not hesitate to perform a test right away. If any of the parameters such as pH values or ammonia levels are out of the ideal requirements, you should intervene as soon as possible to help your fish.

If you keep your koi inside a pond, this may be one of the less ideal homes to care about, as there are so many external influences that are out of your control.

One of your fish may have died recently and you are not able to see the body, or some plants have started decaying but you cannot notice them because of the super-lush vegetation in your garden.

These are all normal things to happen, but testing your water constantly is the only way to be aware of them and the necessity to intervene.

Please also remember to ensure that the water temperature is suitable, as well as that there is enough shade for your fish to hide.

Lack of Oxygen

Ponds may sometimes lack of oxygen, as such setups are quite specific thanks to basically having no water current. If this is happening to your koi pond, it should be really easy to rule such a thing out, because your fish will literally be gasping for air at the surface.

And jumping. In such cases, they are simply not able to breathe inside their water environment, so they do all in their power to get out of such water.

Live plants are a greatly decorative yet effective way of increasing oxygenation levels across a pond, so ensure you have plenty of those. Moreover, they will also act as a refuge to your fish whenever they feel frightened or threatened.

Or when the sun is too strong. Additionally, investing in a simple and affordable air stone or any other kind of aeration gadget will certainly improve your water’s ability to offer great breathing conditions.

Chlorine (Due to Water Change)

Even though chlorine is perfectly safe for humans in standard amounts, it can become deadly for fish. If you have performed your regular partial water changes but forgot to de-chlorinate the fresh water you are putting inside their pond or tank, this may be the reason for seeing them jumping and flashing.

Each time that tap water is placed into a fish home, even in the smallest possible amounts, it has to be treated with an apposite de-chlorinator. If this is skipped, water will become a deadly hazard for your fish. Chlorine may literally cause chemical burns and kill your fish if not treated immediately.

Disease or Parasite

Another discomforting reason which may make your koi fish to jump and to flash is pain or irritation. If your fish are suffering from a disease, which may be caused for multiple reasons, they may be in pain.

That means that may start acting erratically out of desperation. Very similarly, if they are affected by a parasite or bacteria, this may cause serious irritation and itchy feelings. In such cases, most of the koi wish will try to alleviate such discomfort by jumping and then by scratching onto rocks or plant surfaces.


If your fish are exposed to too much direct sunlight, this may cause skin burns and they may soon start flashing in a desperate attempt to cool down and alleviate the pain.  

Sunburns may be extremely dangerous for koi fish and they happen more often than we like to believe they do. Especially when they live into outdoor ponds.

However, they are easy to spot as they literally look like burns and can therefore be treated immediately.

Wrapping Up

Now that we have gone through the main reasons which may force your koi fish to jump out of their pond, you should be able to distinguish them and react when needed. And remember, koi fish are playful creatures, and they may certainly jump out of happiness, too.

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