Do Koi Carp Sleep?

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One of the most common questions we get asked is ‘do koi carp sleep’.You may assume that koi do sleep at some point, but is that correct? And, if so, how do koi sleep? How often do they sleep? And how can you tell they are sleeping? Read on to learn more…

What do we mean by sleep?

When we think of sleep, we generally mean a period of inactivity where we close our eyes, relax our bodies and lose consciousness as our brains and bodies refresh themselves.

Dreaming and the different stages of sleep are an important part of this, and the sleep of mammals goes through distinct cycles before we wake up in the morning.

The differences between fish and mammals

Koi carp are not mammals, and so, sleep for them is not the same thing! Fish such as koi carp do not have the same higher-level brain functions that mammals do, and so they do not and cannot follow a similar type of sleep process to us, and as far as we know, they do not dream.

Another way in which koi sleep differs from human sleep is that koi do not close their eyes. This is because they can’t, as koi don’t have eyelids!

Ultimately, there is some debate among fish experts over whether or not the resting and rejuvenation process of fish like koi carp can genuinely be viewed as “sleep” or simply as deep rest. But one thing we can be sure of is that koi go through cycles of minimal activity daily, where it is fair to say that they are at least deeply resting, if not actually “asleep”.

Brain function and resting

You can often tell when your koi are undergoing a rest cycle by watching their activity levels. When at rest, koi will float still in one spot of the pond for a long time, usually in the middle or near the bottom of the pond, to avoid exposing themselves to predators.

Cold weather also affects koi, and they may, in extremes of cold, go through a process of semi-hibernation, where their metabolic rate slows right down, they do not feed, and they will retreat to the bottom of the pond to wait out the cold snap. When the weather warms back up again, they will return to life and resume feeding as normal.

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