Why Are My Koi Active At Night?

The chance to raise your very own koi pond, full of beautiful fish that look simply majestic as they swim through the water, can be a lot of fun. But it’s also a massive undertaking.

These are intelligent creatures, and you must give them the care and comfort that they deserve. To take proper care of their pet koi fish, koi keepers must be aware of their pets’ unique behavioral patterns.

Understanding why your pet koi fish behave a certain way will enable you to look after them better.

For example, you must have an understanding of their sleep patterns. A shift in your koi’s sleep pattern or unusual behaviors related to sleep could potentially be a sign that your pet koi is sick.

Are your koi getting enough sleep? Or are they sleeping too much? Are your pet koi fish sleeping at the appropriate times?

Knowing the answers to such questions can be the difference between life and death for your pet koi fish.

This article will elaborate upon certain koi behaviors related to sleep, and why they behave the way they do, during specific hours of the day.

Do Koi Fish Sleep at All?

Do koi fish ever sleep? To the uninitiated, this might seem like an all too easy question to answer, but experienced koi-raisers know better. Like most fish, koi don’t have eyelids.

This means it can be difficult to tell if they are sleeping or not.

Science hasn’t been able to conclusively determine if koi do in fact experience sleep the same way we do. What we do know is that they tend to enter a state of stillness, during which they barely move.

The Evolutionary Explanation

One theory about this phenomenon is that it allows them to trick predators. If predators can never tell when koi are asleep, and when they’re alert enough to run away, they’ll be discouraged from going after them.

How Koi Sleep Is Different from Humans

As you may well know, science tells us that as human beings, we all require at least 6-8 hours of sleep for our minds and bodies to function to their full capacity. Koi fish don’t need sleep the same way humans do.

Instead, they enter a short state of rest a few times throughout the day, during which their bodies are almost completely motionless.

How To Tell When Koi Are Resting

So, what do koi look like when they’re resting? If you want to observe your koi resting, look out for those koi that have moved closer to the bottom of their pond.

A resting koi will hide below the surface of the water and remain almost perfectly still.

You’ll see your resting koi hovering. This is just the slight motions of the water moving their dormant bodies, rather than them moving of their own volition.

If you’re observant enough, you may even notice their fins twitching occasionally as the rest of their bodies remain perfectly still.

When it’s time to feed your koi, look for the ones that are resting at the bottom of the koi pond.

You’ll notice that when you toss their food onto the surface of the water, the ones that are wide awake come rushing to eat first.

It takes a second for the resting ones to be alerted before they join their fellow pond mates for lunch.

How To Help Your Koi Rest

To facilitate your koi, you must provide them with a habitat in which they feel safe and comfortable. This involves decorating the base of their pond with plants and rocks, so that they can sleep nearby.

There are a few reasons koi prefer to sleep at the bottom of their koi pond. First of all, sleeping at the base of the koi pond helps your pet koi fish stay safe from predators.

Secondly, the water at the bottom of the pond is colder, which causes your koi’s body temperature to decrease, thus lowering their metabolism and allowing them to rest peacefully.

If you can successfully provide a naturalistic environment for your koi, they’ll be able to exhibit the same sleeping pattern and behaviors that they do in their natural habitat.

This will enable them to grow healthier and live longer.

Do Koi Sleep on Their Sides?

No, koi never sleep on their sides. As mentioned above, when resting, koi hover peacefully under the water. If you do happen to see one of your koi floating on the surface of the water, on its side, this means something is very wrong.

Your koi is probably sick or dying, if not already dead. We recommend seeking medical attention from a professional vet immediately.

Do Koi Fish Sleep at Night?

Yes, koi generally tend to go dormant toward the late evening, once the sun has almost completely set.

They don’t immediately enter a state of rest, but gradually you’ll notice your koi descend to the bottom of the water and stay there until the early morning.

Are Koi Nocturnal?

Some people may think koi fish are nocturnal, but this is a misconception. If your koi are active during the night, it means that something has gone wrong with their regular sleep cycle, and you should take the necessary steps to correct it.

Do Koi Require Darkness?

Koi fish are wild animals; they originated in bodies of water near rice farms in Japan. Because of this, they don’t require extra darkness or extra light.

The ideal environment for them is outdoors, with as much light and dark as is provided by nature itself.

This means you don’t need to put a light source near their pond or use a cover to make it darker than it needs to be.

Koi can still see just slightly in the dim moonlight, which allows them to maneuver comfortably through their pond at night. Making it any darker could frighten your pet koi fish.

Do Some Koi Remain Active at Night?

Sometimes, you may notice some of your koi remaining active at night. This isn’t natural, but it doesn’t necessarily mean your koi are sick, or in any danger.

There are a few reasons your koi might not be sleeping when they should be. It’s important to know what these reasons are, so you can deal with each of them.

Why Your Koi Aren’t Sleeping at Night

If you notice your pet koi fish splashing energetically when they’re meant to be resting at the bottom of their pond, there could be something about their environment that is making it difficult for them to sleep.

Perhaps there is too much noise pollution in the area, or too much light directly over their pond. It could also be that the nutrient levels of the water are unbalanced. Perhaps the temperature isn’t ideal, or the pH levels are either too high or too low.

It’s important to monitor each of these factors carefully, and continuously optimize the conditions of your koi pond, so that your pet koi can remain healthy and happy.

The other possibility is that your koi are hungry at night. During the night, insects might collect along the surface of the water. Perhaps your pet koi fish enjoy snacking on these insects, so they stay awake to do so.

Are you feeding your koi at the appropriate time? Try feeding your pet koi fish a little sooner in the day, and see if that makes a difference to their sleeping habits.

It may be the case that a predator is bothering your pet koi. For example, you may have stray cats or raccoons trying to attack your koi while you aren’t around.

Fear of being attacked by a predator could be preventing your pet koi fish from sleeping.

We recommend installing a camera near your koi pond, so you can monitor activity that takes place when you aren’t around. If you do happen to notice a predator threatening your pets, consider installing a fence around the koi pond.

If you follow the advice detailed in this article and your pet koi fish are still active during the night, you may want to personally consult a vet that specializes in koi fish.

Such a vet might prove expensive, but it’s a necessary investment to make to keep your pet koi fish happy and healthy.

What Do You Think?

Are you already an experienced koi fish keeper? If so, have you ever experienced any of the unnatural sleeping behaviors discussed in this blog? What have you done to help correct them? 

Or, are you new to the wonderful hobby of koi raising? If so, do you intend to use the advice given in this article to help raise your pet koi fish?

The fact of the matter is, koi raising can be a lot of fun. You’ll get the unique experience of bonding with these magnificent creatures.

However, raising your pet koi fish is a massive undertaking and not one you should ever take lightly. We recommend doing ample research, so you can give your pet koi fish the care they deserve.

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