How do fish sleep in an aquarium? Learn here.


Sleep is the most important period of life for any living organism, and aquarium fish are no exception. In this article you will learn about what happens to aquarium fish during sleep and how they experience this process. You’ll learn about how different types of aquarium residents sleep.

Fish hibernation in aquariums

If you have ever observed the behavior of the inhabitants of an aquarium, it may seem to you that they are always active and never sleep. However, this opinion is not correct. In fish, as in all wildlife, the periods of activity are replaced by slower behavior. This is the process of their sleep.

A distinctive feature of fish life is the inability to fall into deep sleep. Their brains do not shut off completely, but during the hibernation period you can see a significant slowdown in movement (you could see the animal just freeze in the water, almost without moving). It is worth noting that many inhabitants of the aquarium, during hibernation, are attached to algae or hiding in secluded corners. During the sleep period all the processes of life are slowing down, so the animals are looking for the most comfortable place to enjoy peace and quiet.

However, the fish remain conscious, as different hemispheres of their brain continue to function. Therefore, as soon as the fish will feel danger, it will immediately go into an active state, allegedly waking up. Since these residents of the aquatic environment do not have eyelids, their eyes are constantly open, even during sleep.

Sleep phase for a fish may last only 5 minutes, depending on the type and the presence or absence of stressors (light on, strong noise, etc.).

Different fish species sleep differently

There are certain differences in the sleep mode of fish of different species. For example, the majority of aquarium residents are bone species. They are able to hibernate and float in the water in an almost immobile state. They have a swimming bubble, which is filled with air inside them. Therefore, the more air it contains, the higher the fish can float in an aquarium.

However, there are also cartilaginous fish, which do not have such a bubble. These include an encystrums and boes. They are able to fall asleep, but do so at the bottom of the fish tank. In addition, there is a subspecies – parrot fish. Its representatives fall asleep, forming a so-called blanket around them. They are able to secrete mucus and envelop it. This guarantees them a certain protection from various stress factors. There are also varieties of aquarium residents who need to install special places like caves, where they hide for the duration of sleep.

It is also worth remembering that different species of fish are awake at different times. Most of them sleep at night. So you may have seen the fish come alive and become more active when you suddenly turn on the lights at night. It is worth understanding the differences in the behaviour of many species of aquarium fish if you want to learn more about the nature of their life.

Why It Is Important To Understand Fish Sleeping Habits

As you now know, different aquarium fish have different sleeping habits. The only thing that they have in common is the fact that their consciousness does not turn off completely, as it does in many other animals. You should be aware of the specifics of hibernation if you want to enrich your knowledge or create the best possible environment for your aquarium pets. Fish care will require some effort from you, so it is necessary to study all the information, including the features of sleep and awakening.

Remember that fish also have insomnia, which can cause various diseases. To prevent this, it will be necessary to remember the following things:

  • Turn off the night light in the room where the aquarium is located (unless you have twilight fish that are more comfortable to watch at night);
  • Learn about the life and behavior of fish before buying them. Learn as much information as possible about favorable living conditions and ensure that they are as good as possible;
  • Plant the aquarium with dense vegetation if you buy fish that sleep during the day. This way they can hide in the vegetation and relax.
  • Fish reduce their physical activity for a certain period of time. This helps them to rest and stay healthy.

If you decide to buy fish as pets,make sure they live in a comfortable environment. Remember that if the fish is constantly stressed, it won’t be able to rest. Therefore, it is important to provide it with complete safety, even during hibernation. Take care of your fish and enjoy their beauty!

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