Does Aquarium Fish Sleep?/ A Comprehensive Guide!

Everyone needs a good night’s sleep to get rid of tiredness and give the mind a rest so that it can keep on working properly without having any sort of issues. However, do aquarium fish sleep?

Yes, fish do sleep, but their way of sleeping is quite different from humans. Some fish sleep by being completely motionless, while others, like tuna and sharks, sleep while swimming. It is impossible for them to breathe if they are not moving. Even when they’re sleeping, they need to move.

Does Aquarium Fish Sleep?

The answer is yes; aquarium fish do sleep whenever they get tired. However, the way fish sleep varies according to species.

Does Aquarium Fish Sleep

Some fish fall asleep entirely and get motionless when they’re sleeping, while fish like tuna and some sharks have to keep moving when they’re asleep because they can’t breathe without moving.

What about blind cavefish, though? Well, they’re the kind of species that don’t sleep entirely.

How fish sleep differs from human sleep?

Fish and humans have different sleep styles.  While we need a comfy bed and a dark room to sleep, fish can take a nap just about anywhere in the water. They don’t have to close their eyes or get all cosy; they just sort of drift off into a trance.

Some fish can even sleep on the move! Can you imagine sleeping while walking or running? Crazy, right? Sleeping wherever and whenever they want, fish really have a life.

What are the factors that affect the sleep of fish?

The following mentioned factors affect the sleep of fish. Let’s take a look at them.

  • Water Temperature: The ease with which a particular fish can nod off depends in great part on the water’s temperature. For a certain type of fish to stay content, healthy, and comfortable, the water must be at a specific temperature. As a result, fish will have an easier time falling asleep when the water is at a temperature that is suitable for them.
  • Availability Of Food: Giving your fish too much food will make the tank dirty, which will make it harder for them to sleep in the poorer water. On the other hand, if you don’t feed your fish enough, they’ll be continually anxious about when they’ll get their next meal and find it harder to fall asleep.
  • Decorations And Accessories: Fish generally sleep better in tanks that have a lot of decorations and hardscapes scattered throughout the tank. Due to the decorations often limiting light entering the tank, fish are able to hide and relax in shadows in addition to having a wider choice of sleeping locations.
  • Tank Size: The size of your fish tank has a big impact on how well the fish can sleep because various-sized tanks typically have different illumination levels. More specifically, because there is more water and the aquarium is deeper, larger tanks with more water tend to scatter varying amounts of light.

How Do Fish Sleep?

Now, most of you would want to learn how to wake a sleeping fish. Therefore, fish sleep differently than humans. 

Unlike humans, who close their eyes and become unconscious, most fish simply slow down and reduce their activity levels. It is even possible for fish to swim in place, staying in the same spot for long periods of time.

For example, clownfish will hide in their anemones during the night and become less active. They’ll swim around more slowly and make fewer movements than they would during the day. Similarly, catfish will burrow into the mud and become more still.

Different species of fish have different sleep patterns. Some animals, such as sharks, never truly sleep because they must keep swimming to keep water flowing over their gills.

But even these species will slow down and rest for brief periods. Other species, such as eels, will actually coil up and become completely still.

Simply put, while fish may not sleep like humans, they still have a way of taking breaks and resting their bodies. And each species sleeps differently.

How Long Do Fish Sleep?

Well, fish don’t exactly sleep as we humans do, but they do have times when they take a nap, so to speak. Fish species vary depending on their characteristics.

Some fish might only take quick power naps here and there throughout the day and night, while others might rest for a bit longer. But, it’s not like they’re counting sheep or anything. It’s just a period of reduced activity for them.

Sleeping Time Of Different Aquarium Fish

Now, I’m going to tell you the sleeping time of the most common and famous aquarium fish. Let’s dive in!

  • Pomacanthus: Starting with the Pomacanthus, these guys tend to take quick power naps throughout the day and night, just like other fish. Nothing too crazy, just some downtime.
  • Emperor angelfish: The Emperor angelfish is a bit different. These fish might rest for slightly longer periods, but still, nothing compared to how humans sleep.
  • Blueface angelfish: The Blueface angelfish is similar to the Emperor angelfish in terms of sleep patterns. Snoozing might last a little longer, but not for too long.
  • Koran angelfish: The Koran angelfish is also in the same boat. They’ll take some rest, but not for hours on end.
  • rest, but not for hours on end.
  • Queen angelfish: And finally, the Queen angelfish. These fish will also take breaks, but again, not for extended periods like we do when we sleep.

So, there you have it! Different species, different sleep patterns. But one thing’s for sure, these fish are always ready for a swim!

How Long Do Aquarium Fish Sleep?

Aquarium fish can have different sleep patterns, just like their wild counterparts. Some species may take quick power naps throughout the day and night, while others may rest for slightly longer periods.

However, it’s important to note that the sleep patterns of aquarium fish can be affected by factors such as their environment, the presence of other fish, and their feeding schedule.

So, it’s kind of like a mixed bag—some aquarium fish might sleep for a bit, while others might be more active. But either way, they’re always ready for their next meal or a swim around their tank.

What Are the Signs That a Fish Is Asleep?

What would you do if you wanted to know if your aquarium fish were sleeping? It’s hard to tell if a fish is asleep since they don’t close its eyes or show any noticeable physical signs. But here are a few ways to tell:

  • Observe their behaviour: Fish tend to become less active and swim slower when they’re resting. They may also spend more time hanging around in one spot or near the bottom of the tank.
  • Check their gills: If a fish’s gills are moving slower than normal, it’s an indicator that they’re in a state of rest or sleep.
  • Don’t disturb them: If you want to make sure a fish is getting some shut-eye, avoid tapping on the tank or otherwise disturbing them. A sleeping fish will quickly swim away if they’re startled.

When Do Fish Sleep?

Fish sleep patterns vary just like human sleep patterns, some fish are active during the day, others at night, and some in the twilight hours. 

Diurnal Fish:

These fish are active during the day and sleep at night. Think of them as early birds. Some popular diurnal species include guppies, angelfish, and tetras. They need plenty of light to be active, so make sure their tank is well-lit during the day.

Nocturnal Fish:

During the day, nocturnal fish sleep, while at night, they are active. These fish are night owls and usually rest during the brightest hours. Some popular nocturnal species include catfish, loaches, and some cichlids.

It is important for them to have plenty of hiding places and low light levels in order to feel comfortable.

Crepuscular Fish:

Crepuscular fish are active during twilight hours, both at dawn and dusk. These fish are the in-betweens, not quite diurnal and not quite nocturnal. 

Some popular crepuscular species include rainbowfish and some species of shark. These fish can adapt to either a day or night schedule, depending on the lighting in their tank.

In summary, fish sleep patterns are a result of their natural habitat and survival instincts. Some fish are active during the day, others at night, and some during twilight hours.

Keep their natural patterns in mind when setting up their tank to give them a comfortable environment to rest and play.

Is complete darkness necessary for fish to sleep?

Not necessarily. Fish don’t have eyelids to close, so complete darkness isn’t necessary for them to get some shut-eye.

However, a low light level and plenty of hiding spots in the tank can help create a more relaxing and restful environment for them.

It’s important to consider the specific species of fish you have and provide them with the environment that most suits their needs, such as nocturnal fish.

In general, a consistent and stable light and dark schedule can help establish a healthy sleep cycle for your fish.

Is it true that fish sleep at the bottom of the tank?

According to the fish species, it varies. Some fish do rest near the bottom of the tank when they’re sleeping, while others might find a hiding spot among plants or decorations or simply rest in a particular area of the tank.

For example, bottom-dwelling species like catfish or loaches might spend a lot of time near the substrate when they’re resting.

On the other hand, other fish might hang out near the surface or in the middle of the tank when they’re sleeping.

It’s important to provide plenty of hiding spots and resting areas for your fish so they have a comfortable and safe place to sleep, no matter where they prefer to do so.

And remember, a low light level and a stable routine can help create a calm and relaxing environment for your fish to get a good night’s sleep.

In a fish tank, do fish sleep at the top?

Typically, fish won’t snooze at the top of the tank. They might be acting in this manner as a result of a lack of oxygen in the water.

Water at the surface contains more oxygen. There might be a need to obtain oxygen up there, so they might be attempting to do so.

Do fish sleep upside-down or sideways?

There are many positions in which fish can sleep, including upside-down and sideways. According to the species of fish and their sleeping habits, it varies. 

Some fish may float upside down when they’re resting, while others might rest against the side of the tank or sink to the bottom.

When a fish sleeps, what happens?

When a fish sleeps, its body functions slow down, including its metabolism, heart rate, and movement. There is a decrease in their activity and may even be a decrease in their response to their surroundings.

During this time, the fish’s body can conserve energy, repair and regenerate cells, and perform other important functions that help it stay healthy and strong. 

Just like us humans, a good night’s sleep is essential for a fish’s overall well-being and ability to thrive in its environment.

Is a fish sleeping or dead?

When a fish is sleeping compared to when it is dead, there is a difference. To find out whether your fish is sleeping or dozing, you have to consider the following factors: It can sometimes be tough to tell if a fish is sleeping or has passed on. However, there are a few signs to watch out for.

  • If a fish is sleeping, it’ll usually find a hiding spot and stay very still. It may also slow down its gill movements and have a more relaxed posture.
  • If a fish has died, it’ll usually float belly-up and may have a cloudy eye or discoloration. Its gill movement will also stop completely.
  • It’s important to regularly check on your fish to make sure they’re healthy and happy. And if you suspect one has passed, remove it from the tank as soon as possible to avoid any negative effects on water quality and other fish.

Importance of providing a suitable environment for fish sleep

Providing suitable sleep for your aquarium fish is important for a number of reasons.

  • Proper rest helps fish recover from the stress and exertion of their daily activities.
  • A healthy immune system and reduced risk of infections and diseases are benefits of good sleep for fish.
  • Fish that are well-rested are more active, and energetic, and feed more efficiently, leading to improved overall health and growth.
  • A good sleep environment can also help reduce the risk of injury or aggression among fish, as they are less likely to become stressed or frightened in their sleep.
  • In some species, sleep is essential for the proper development and growth of their nervous system.
  • Adequate sleep can also help regulate a fish’s circadian rhythms, leading to more stable behaviour patterns and improving overall well-being.

So, as you can see, providing a good sleep environment is essential for the overall health and well-being of your fish.

As a result, you now know almost everything there is to know about sleeping in an aquarium.

Final Words!

In conclusion, fish do sleep, and it is essential for their overall health and well-being. Just like any other living organism, fish need proper rest and a good sleeping environment to function optimally. 

By understanding the different stages of sleep in fish as well as the factors that impact the quality of their sleep, aquarium owners can ensure that their fish receive the rest they need.

So, the answer to the query, “Do aquarium fish sleep?” is a resounding yes!

You are responsible for providing a safe and comfortable environment for your fish if you own an aquarium

This will not only improve their health but also make your aquarium a happier and more enjoyable place to be.

To make the most of your aquarium and give your fish the best life possible, take the time to learn about their sleep needs and implement appropriate measures to promote restful and restorative sleep.

That’s it. If you have any questions related to the topic, please let me know in the comment section below. I’d love to help you out.

Umer Javed

Umer Javed is the principal creator of, a website dedicated to Aquarium fishing guidlines. We're dedicated to providing you the best of Aquarium Fishing, with a focus on dependability and Aquarium. We're working to turn our passion for Aquarium Fishing into a booming online website

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