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How Do Fish Sleep?

Do fish sleep? And how do fish sleep? These are probably the most common questions that pop in mind whenever we look at a fish.

Those tiny little creatures with no eyelids hover around the water all time. But how do they get the energy to stay active all day? Do they take a power nap in between? Even if they do, then how? These are some typical questions that keep gathering in our minds.

If you are wondering, do fish sleep, the answer is yes. How? Their way of taking rest is different from ours. They stay motionless with slow breathing movements. Fish usually sleep near the bottom or middle column of the water for 8-12 hours and remain active all day long.

Do Fish Sleep?

Yes. Fish do not sleep similar to mammals. To keep up with the energy for the whole day, they need to take some quick rest, which keeps them functional for the entire day.

According to researchers, fish can effectively reduce their activity and metabolism rate while resting. They tend to be motionless and breathe slowly when they are asleep.

But they do remain alert about any danger that can come in their way while sleeping.

How do Fish Sleep?

Fish have no eyelids, it’s difficult to recognize them sleeping by looking at their eyes.

They have a habit of lying completely motionless when they feel the need to rest.

Their brain makes them slow enough to respond to things going on around them.

You can even see that some fish do not respond at all.

Don’t think them to be dead!

If you notice closely, you will see that their gill movement becomes very slow as their breathing slows down while resting.

In The Ocean

Ocean fish sleep in a similar way mentioned above.

The ocean is wider and there are many chances of getting attacked by predators or becoming someone’s prey, fish residing in the ocean are more alert.

Most ocean fish prefer staying in a shoal, which makes them rest altogether in a group.

Some of the fish like to hide in the corals to sleep safely.

Some fish prefer to sleep, floating in one place.

In An Aquarium

As fish are introduced to a tank, they may face insomnia in the initial days. But as soon as they get familiar with the tank, the fish will feel safer to rest.

You can find them near the bottom, in the middle column, or at the surface area of the water.

Bottom feeder fish like catfish prefer to lie down near the bottom area of the tank or over the sand substrate.

If a fish is not a bottom feeder but still tends to stay gathered at the bottom area, then you can take it as a sign of illness or weakness.

When it comes to shy fish, they prefer to sleep inside the hiding spots, safeguarding themselves from predators and attackers. They like to stay hidden there when they don’t feel like facing the world.

Sleeping Duration

Fish require more rest than land mammals.

Similar to humans and other animals, most fish species tend to sleep at night.

Most of the fish you will come across are diurnal by nature, i.e., they move and perform all activities during the daytime. And they prefer to rest in the night hours. They require an average of 8-12 hours of sleep every day to keep their functions active.

Some species are nocturnal and mostly become active at night. These nocturnal fish sleep during the entire daytime in a crevice or at any place where they prefer to stay hidden.

Lighting Conditions

Fish do not require darkness for their sleep. They can do fine with lights on.

It is recommended to turn off the lights of your aquarium during nighttime, as most of the diurnal fish won’t understand if it is day or night.

Switching off the aquarium lights will help them know that it is nighttime and they must sleep now. It will help them to maintain a continuous sleep routine.

Sleeping Position

Are you wondering, do fish sleep upside down or sideways? Here are the answers:

Upside Down

A sleeping fish is probably stationary, but it stays upright. They do not try to turn sideways or even upside down.

If you notice a fish sleeping upside down, it may not be well. Usually, fish having ailments in their swim bladder tend to lie sideways by their body or upside down.

Swim bladders are the organs that help in maintaining their buoyancy. So, when they have issues with their bladders, they might get upturned.


That is completely dependent on their comfort level and sleeping pattern.

If you have a broad-leafed plant in your tank, then you can often see your fish lying on their side near the broadleaf to get some more comfort and serenity.


Did you just notice your fish move a bit while sleeping?

Don’t worry, this is nothing unnatural about them. Most of the time, fish tend to move while sleeping to keep themselves partially aware. It helps them to stay alert from predator fish, or birds, which feed on them.

There is also another reason why most fish species move even when they are asleep. It helps them to get a constant supply of oxygen as the flowing water passes through their gills.

Frequently Asked Questions

Is My Fish Sleeping or Dead?

If you are an aquarist, the first thing that can come to your mind while seeing a fish motionless is whether it is dead or just sleeping.

You need to look for some signs in them to determine this.

If your fish float at the top of the tank, then it can be a concern for you. It can either mean that the fish is dead or injured enough to move.

If you find your fish to lie at the bottom area atop the tank’s substrate, then probably the fish is no more.

Whenever you are in doubt regarding things, make sure to look for the signs of life in it.

Check whether the fish’s gill has any movement during breathing or not.

You can also touch the fish gently. If it moves away or starts swimming, then undoubtedly it is alive.

If it does not respond, then it is certainly dead.

When you see them motionless, don’t always panic, investigate the matter following the above-said tactics and then conclude.

Do betta fish sleep upside down?

It may be common for bettas to sleep on their bellies.

You can see them resting upside down occasionally. This activity of your fish can be concerning for you. You must check immediately if the fish is sick or not.

How much do betta fish sleep?

That is utterly dependent upon the individual fish.

You might sometimes notice betta fish sleep during the daytime, or sometimes you can find them taking a long nap at night.

Light plays a significant role in sustaining the routine of fish, you can control your betta fish’ sleeping with the aquarium lights.

Where do betta fish sleep?

Most of the time, you can find your betta fish lying near the gravel. It is quite normal behavior for them to lie and sleep in the bottom area of the aquarium.

It is better to stay cautious about the signs for their health.

Do goldfish sleep?

Yes, they do take some rest to cope with their busy schedule of swimming around.

Goldfish do not naturally sleep in the night, similar to land mammals.

All they need to have is a dark and quiet ambiance. Goldfish prefer to take a power nap whenever the tank environment is dark and quiet.

It is better to keep the noise level low when your goldfish is sleeping, or else they can awaken.

Do catfish sleep?

It depends on the type of catfish.

While a few catfish species prefer to have a sound sleep at night, others are nocturnal and prefer to stay awake at night and sleep in the daytime.

Do jellyfish sleep?

Jellyfish do sleep.

Jellyfish do not have brains, yet they still feel the need to sleep. Sounds weird, right!

Do clownfish sleep?

Yes, they do take short naps to keep themselves active. You can find a clownfish sleeping on its side at the surface area of the tank.

You can find them adopt a shell or remove the inside of a piece of coral as a pseudo-anemone and stay near or in this host to sleep well.

They will stay awake for the whole day if you do not switch off the aquarium lights. They mostly prefer darkness to fall asleep.

Do starfish sleep?

Starfish do not sleep.

You can often see starfish come out from their hiding areas during darkness or in the evening. It makes us assume that they sleep throughout the day.

The reality is entirely different.

Starfish prefer to hide themselves during the daytime. In the daylight, they spend their time waiting for suitable periods when they can come out and prey.

They barely sleep or take rest, unlike other sea creatures.


So, now you have the answer to both the questions, ‘do ever sleep’ and ‘how do fish sleep.’

Similar to most other species in the world, fish also require sleep to stay healthy and active.

Their sleeping cycle is as crucial as ours, as it keeps them fresh, boosts their immunity, and prevents sleep deprivation.

If you are keeping some fish in your aquarium, make sure they get a proper amount of sleep as per their requirements.

If any time you notice something unusual in your fish’ sleeping behavior, be cautious enough to check if they are asleep or injured.