How Do Fish Sleep In A Tank? All You Need To Know!

How do fish sleep in a tank
How do fish sleep in a tank? Most living organisms sleep; it is an essential part of life. Fish is no exception to this; however, the water living organisms sleep or rest are different from land-living organisms.
Most of us have this question, how do fish sleep? Mainly, the one who has an aquarium tank raises this question, and some enthusiasts don’t just question but try to observe how do fish sleep in a tank? Because fish neither close their eye nor cozy-up with a blanket to sleep.
Many vital functions of an animal’s body, such as cell repair, energy replenishment, and processing information, are performed during the resting state we define as sleep. But does the surrounding habitat of an animal affect its ability to sleep and perform these functions, as mentioned earlier?
How do fish sleep in a tank compared to their natural habitat of vast oceans, flowing rivers, streams, lakes, ponds, etc.?

The Age-Old Question “Do Fish Sleep”?

The question ‘do fish sleep’ stems from the highly unconventional manner in which fish perform this task. The neurological biology of fish differs vastly from most other animals. They do not have a neocortex and cannot carry out the functions associated with the neo-cortex. The absence of neocortex, combined with the fact fish do not have eyelids, has led many to question whether the resting states of fish can be defined as sleep

Recently, Stanford University conducted a study on identifying the sleeping patterns in fish. The researchers recorded the fish’s brain activity to determine how do fish sleep in a tank. For this study, they used Zebrafish as they have a lot in common with humans. Besides their inherent lack of rapid-eye-movement and eyelids, fish’s brain activity suggests signatures similar to most mammals, reptiles, and birds. In essence, fish do sleep, just in a slightly different manner than we are used to.

How Do Fish Sleep in a Tank?

Fish are unique species. They have two distinct manners of sleep. They can indeed go into a state called alert to sleep. In this case, the brain is asleep, but the fish’s senses are pretty much vigilant to any potential dangers. When fish go into their actual sleeping state, their breathing slows down, and they can exhibit several different behaviors according to their species.
While most fish may remain motionless such as Mozambique tilapia, some, like the Cichlids, may switch between staying stationary to suddenly moving around as if waking from some trance. Some fish have to keep moving even while they sleep to keep their gills ventilated. Some species such as the Parrotfish and Wrasses wrap themselves in a cocoon of their mucus. Yes, you read that right; this practice helps them ensure a good night’s rest without the fear of a predator not maintaining their social distance.

How do Goldfish sleep in a tank?

Goldfish have specific changes in their motions; Goldfish while sleeping,  tend to stay and maintain stability in their movement. They hover around at the bottom of the Tank no more than an inch (2.5cms) from the bottom with their head slightly downward. During their sleep, Goldfish will fade their colors as a means of protection from predators.

How does Betta sleep in a tank?

how do betta sleep in a tank

Betta finds different places and positions to sleep in a tank. Some Bettas nestle themselves on the substrate; some find decors like crevices or caves to sleep in; while some float around at the surface.
New Betta owners, don’t be alarmed when you find your Betta in funny positions; they rest like any other living organism.

Where do Fish sleep in a tank?

Different fish have different preferences. Not all fish sleep the same way nor in the same place. Many fish types prefer to lay at the Tank’s bottom and sometimes bury themselves in the gravel or sand or under a rock like Bettas. That may alarm many fish owners to find that their fish has suddenly disappeared into thin air, only to find it back a few hours later. Some fish choose to hide in caves or crevices for the night, and others, others don’t care. They float around motionlessly around the surface of the Tank, nestling into plants, corals, or other objects, often just using their fins to maintain balance.
When Do Fish Sleep?
An interesting fact about fish is that, similar to humans; melatonin plays a big part in a fish’s sleep mechanisms. Although frequent napping is common in many fish, most of them are diurnal. In that, they move around in the day and fall asleep during the night. However, some species are nocturnal, such as Kuhli loach, Amano Shrimps, Red Cherry Shrimps, Catfish,  etc.
Knowing whether your fish are diurnal or nocturnal could be helpful if you’re looking to keep multiple species of fish in a community tank.
For instance, Neon tetras, a diurnal fish, next to Pictus Cats, a nocturnal fish, may result in conflicts about how do fish sleep in a Tank. The Neons likely to sleeping huddled up at night while the Pictus prowl for food, not a great combination.
When you have a community tank, you need different species with different purposes to maintain the Tank’s eco-system. For example, you need species that dwell at the bottom; some species reside in the middle and the surface. You also would need a set of cleaning crew. Hence, you would want to choose the species that can live together without posing a threat to one another.

Do all fish sleep then?

That’s not exactly true either. Many fish don’t sleep when caring for their young or migrating, some like the Tilapia, don’t sleep until they are six months old; the blind cavefish don’t sleep at all!
In the wild, fish do not sleep while migrating. Aquarium fish such as Clown Loaches are migratory in the wild.

Do fish need Darkness to sleep?

Well, in most cases, quite simply, yes! How do your fish sleep in a tank largely depends on the sleeping schedules you set for your fish! Keeping a consistent day-night situation helps maintain a healthy sleeping schedule for your fish. Like humans, fish have similar brain chemistry that controls the uptake of melatonin. It is regulated in more significant amounts during the night and less so during the daytime.

How many hours does a Fish sleep?


It is hard to gauge exactly how long a fish sleeps. Fish sleep in 10 – 30 minute cycles throughout the night. In most cases, providing a fish with 10 -12 hours of Darkness will allow it to get the amount of rest it needs. Like people, fish need sleep to restore energy to their body systems and maintain proper immune function. If they don’t sleep enough, they lose their ability to fight off infections, and their metabolism slows.
With the slower metabolism and reduced immune system, the fish will be prone to catching diseases, and consequently, the fish may not live to their optimal age.
If you want your fish to live with you to their optimal age, you for sure would like to take care that your fish has good night rest or day rest, depending on the species.

Do Fish Dream?

By scanning a fish’s brain during their rest cycles, the researchers found that fish don’t go through the same sleep stages as us. There is no change in brain waves during sleeping, and they do not enter the REM stage or the Dream stage, where humans and several other animals like cats, are known to dream. So as far as we can tell, a fish does not dream.

Do Fish sleep upside down?

Healthy fish sleep stationary but upright. It is vital to keep track of how your fish sleeps in the Tank. A fish that leans is lying on the side except with species such as clown loach or upside down isn’t sleeping but is, in fact, more likely to be sick. Most probably, your fish has swim bladder disease.
Swim Bladder disorder, also accurately known as flip-over, is a common ailment amongst fish. A swim bladder is the internal gas-filled organ that allows the fish to remain buoyant without wasting any energy. A disrupted swim bladder may cause the fish to behave unnaturally by flipping over, float on the surface, or sink to the bottom.

Why does my Fish sleep longer than usual?

Sometimes, you may notice your fish sleep longer than usual or perhaps show changes that are not in line with your fish’s standard behavior or routine. For instance, your fish may yawn a lot, start getting aggressive with other fish or staying inactive even during the daytime. These are all signs that your fish is stressed and, if not corrected, may end up being ill as well. Usually, in such a case, we can pinpoint the problem to one of the three issues.

Water temperature in the Tank:

Keeping the water temperature stable with your fish’s requirements is crucial. Depending on the fish species, their ideal water temperature could range from very broad to very narrow. It is essential to identify the right temperature your fish needs and be consistent. Just set the temperature higher or lower for a few hours could cause lots of stress to the fish.

Cramped Tank Conditions.

Not having enough room to swim and move freely due to a small tank or one overcrowded with too many fish and decor leads to injuries and accidents and unwanted behaviors such as fighting over food. Cramped living conditions stress fish out and may lead to future illnesses.

Toxic levels of Ammonia

Fish yawn to clean their gills, and so if your fish yawns constantly, it could be a clear indication of the presence of ammonia in the Tank. The presence of ammonia reduces the amount of oxygen fish can intake and directly affects how do your fish may sleep in the Tank, how they act their appetites and their overall health. It is overly important to test your water and keep adjusting the water parameters regularly; just missing a few water changes could prove to be lethal for your fish.
Ammonia poisoning or spike is one of the common causes why your colorful fishes turn black or turn white and die.
Do Fish suffer from Sleeping Disorders?
In essence, yes. Scientists have conducted studies ( on the Zebra Danios that suggest that the presence and absence of light directly correlate to the sleep inhibiting hormones in fish. Although much more research is deemed necessary to make a conclusive decision. The presence of continuous light/dark could promote sleeping disorders in most aquarium fish.
You encourage your fish to follow a particular sleep schedule with the lighting hours. You can install adjustable aquarium light with a timer to keep up the sleeping schedule.

How do I make sure my fish get enough sleep?

Ensuring your fish get enough sleep boils down to two factors. How long your fish sleep and the quality of how do your fish sleep in a tank. Having a consistent day-night schedule that allows for 12 hours of Darkness and making sure they remain undisturbed during their rest time is vital to getting a good night’s rest.
Getting quality sleep will also depend on the conditions of the Tank. Ensuring your fish have enough space to stay mobile, a healthy eating schedule, and the absence of ammonia in the Tank will directly affect how your fish sleep in a tank.
Like many people, if you’re considering using your aquarium for your night light, it is essential to cover the fish from the daylight to ensure their 12 hours of rest. The day and night schedule is also indispensable for healthy aquarium plants and to maintain a healthy aquarium.

How does sleep impact the fish’s health and longevity?

Sleep or rest is vital for all forms of life. A consistent and quality sleep schedule allows fish to process all information collected during the day, maintain a good metabolism, and remain well-rested during the night and active during the day or vice-versa. If fish’s sleeping patterns remain inconsistent and disturbed, they are very likely to exhibit stressful behavior. They may lose their appetite, be volatile and cranky towards other fish, and eventually suffer from ailments. How do fish sleep in a tank directly affects their overall health and, in essence, determines how long they live as a result.

Do all fish the same way?

goldfish sleeping

Well, in short, no. Although most aquarium fish have similar sleeping mechanisms, their patterns very much vary. For instance, Goldfish usually hover motionlessly around the Tank, often having a slight change of color that protects them from potential predators. The Cichlids, on the other hand, switch around from hovering motionlessly to being suddenly active, whereas Betta fish can choose from several places to sleep in. They may wedge themselves between ornaments, hide under the gravel or inside caves. Like most fish, Betta’s are very light sleepers. They may wake up at the slightest sound or disturbance, and it is crucial to keep them in a quiet place while they rest.


When compared to other house pets, fish are relatively low maintenance. They do not require vaccinations or to be taken for walks. By maintaining healthy living conditions and consistent light-dark routines, fish can live long and healthy lives.
However, a fish owner needs to remain informed of the potential activities and behaviors considered normal and healthy, potentially causing the fish stress. It may take some time and observation to understand your fish’s tendencies comprehensively. But remain patient, and in due time you will surely grow accustomed to understanding your fish and all the intriguing behaviors associated with them.

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