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Do goldfish sleep? All about goldfish sleep

One question that often arises when observing goldfish is, “Do goldfish sleep?” It can be difficult to determine as they lack eyelids and cannot close their eyes. However, goldfish do indeed sleep to rest. They typically sleep for around 12 hours a day, during which they hover calmly slightly above the bottom of their tank. While their eyes remain open, their sleeping behavior can still be identified.

In this article, titled “Do Goldfish Sleep? Understanding the Sleeping Habits of Goldfish” we will explore the topic of goldfish sleep in detail, providing comprehensive information about their sleeping habits. By understanding these patterns, you will be able to discern whether your goldfish is asleep or if there may be other issues at hand.

How do I know when my goldfish is sleeping?

Determining when a goldfish is asleep can be challenging, and many pet owners wonder, “Do goldfish sleep?” Unlike animals with eyelids, goldfish cannot close their eyes or lie down to sleep. However, there are several ways to identify when they are taking a snooze.

One indication is a decrease in activity. If your goldfish appears less active, it is likely that they are sleeping. During their rest, goldfish tend to stay near the bottom of the aquarium, where the temperature is lower—a preference that they have developed over time. They will remain mostly motionless and seem as if they are floating.

How do I know when my goldfish is sleeping?
How do I know when my goldfish is sleeping?

While goldfish do not stick to the floor of the tank, they hover a few inches above the substrate. Additionally, they often lean their bodies at a downward angle, which may seem peculiar. It is important to note that this behavior does not necessarily mean they are awake. Goldfish need to move slightly when they sleep to maintain stability and breathe properly in the water. As a result, their gills and fins may flutter lightly during sleep.

To further confirm their sleep state, observe the color of their scales. Resting goldfish undergo a natural color change, becoming a lighter shade when they fall asleep. This change in color is a defense mechanism that helps them hide from predatory fish in their natural environment. In your tank, it serves as a useful indicator to determine if your goldfish is sleeping.

By understanding these sleep patterns and behaviors, you can better recognize when your goldfish is asleep and differentiate it from other concerns or illnesses.

See more:

How Long Do Goldfish Live? 7 Ways To Increase Their Lifespan

How do Goldfish Sleep?

Goldfish don’t possess a designated sleeping spot in the tank, nor do they lie down to sleep. Just like other fish, goldfish adopt a hovering position within a specific zone in the aquarium. Their fins subtly move during this time to maintain stability, while the movement of their gills aids in respiration.

It could be near the surface, tucked beneath an ornamental feature, or closer to the bottom of the tank. Typically, the head of the goldfish will angle downward compared to the rest of its body.

How do Goldfish Sleep?
How do Goldfish Sleep?

Although we commonly refer to this state as “sleeping” it’s worth noting that goldfish don’t undergo changes in brainwave patterns like humans do. They also don’t experience REM sleep because they remain somewhat conscious during their rest periods.

When you approach the tank, you might observe some eye or body movement from your goldfish. This low-level alertness is an evolutionary adaptation that allows them to detect potential predators even while resting.

When do goldfish sleep?

Goldfish naturally begin preparing for sleep when the tank becomes dark and the environment becomes quiet, typically during the night. In the wild, goldfish have an internal clock that responds to darkness, moonlight, and lower temperatures, signaling them that it is time to rest. In a captive setting, it is important to provide your goldfish with complete darkness and minimal noise to ensure they can sleep properly. Ideally, goldfish should align their sleep cycle with yours, allowing you to observe their active behavior when you are awake. However, disrupting a goldfish’s sleep schedule may interfere with their natural biological clock.

Learn about goldfish sleep

Goldfish sleep is a fascinating aspect of their behavior that many pet owners are curious about. Understanding how goldfish sleep can help ensure their well-being and provide valuable insights into their daily routines. In this section, we will delve into the topic of goldfish sleep, exploring their sleeping patterns, behaviors, and environmental factors that contribute to a restful slumber. Let’s explore the intriguing world of goldfish sleep and uncover the secrets of their nocturnal habits.

Do sleeping fish open their eyes?

Goldfish possess intriguing characteristics when it comes to sleep, and one notable trait is their inability to close their eyes. Unlike many other animals, goldfish lack eyelids, resulting in their eyes being constantly open, even during periods of rest.

This unique attribute serves an evolutionary purpose, allowing them to maintain a certain level of alertness to their surroundings. However, it also renders them susceptible to sudden disturbances. Any sudden movement near the tank or the sudden illumination of the aquarium light can easily startle a goldfish.

Do sleeping fish open their eyes?
Do sleeping fish open their eyes?

Do goldfish sleep at night?

Similar to humans, goldfish tend to rest better in a dark environment rather than in brightly lit surroundings. It is important to ensure that the aquarium light is turned off for at least 12 hours per day to provide them with a suitable resting period.

A practical approach is to align your goldfish’s sleep pattern with your own daily routine. When you wake up in the morning, switch on the aquarium light, and make sure to turn it off no later than 12 hours later, just before you go to bed. This way, you can establish a consistent lighting schedule that promotes a healthy sleep-wake cycle for your goldfish.

Do goldfish sleep at night?
Do goldfish sleep at night?

Do goldfish sleep upside down?

Goldfish do not sleep upside down. It is a misconception that some goldfish keepers may have when they see their fish floating upside down or leaning heavily to one side. In reality, these behaviors are not indicative of sleep but may be symptoms of a condition called swim bladder disease.

If you observe your goldfish swimming upside down or constantly leaning to one side, it is important to research and educate yourself about swim bladder disease. This common condition affects the swim bladder, a gas-filled organ that helps fish control their buoyancy. When the swim bladder is compromised, it can result in buoyancy and balance issues.

To ensure the well-being of your goldfish, it is crucial to investigate and address swim bladder disease promptly.

Do goldfish sleep upside down?
Do goldfish sleep upside down?

Providing your goldfish with a day and night cycle

Establishing a consistent schedule for turning off the lights at night is beneficial for ensuring that your goldfish follows a structured sleeping routine. This practice helps to provide your goldfish with an adequate amount of sleep.

Many aquarium lights are equipped with timers that can be conveniently set using a remote control. This feature is particularly useful for busy keepers who may forget to manually switch off the tank’s light. Additionally, some automatic lights offer a dawn and dusk option, mimicking natural periods of light exposure and enhancing your goldfish’s sleep-wake cycle.

Create a day and night cycle for goldfish
Create a day and night cycle for goldfish

If your light does not have a dimming option, it is advisable to switch it off while there is still some visible light in the surrounding area. Abruptly transitioning your goldfish’s environment from bright light to complete darkness can startle them and potentially disturb their ability to rest for the following hours.

Signs Of sleep deprivation in goldfish

When they don’t get enough sleep, you’ll likely notice signs of sleep deprivation and elevated stress, which can adversely affect their overall health.

For optimal well-being, goldfish require between 8 to 12 hours of complete darkness each day. Failing to provide this necessary downtime can lead to detrimental health outcomes over the long term.

Signs of sleep deprivation can manifest as decreased activity, reduced eating, or heightened susceptibility to diseases due to a compromised immune system.

Goldfish bottom-sitting or sleeping?

Many people mistakenly assume that their goldfish is sleeping when they observe them bottom sitting. However, bottom sitting and sleep have different meanings and implications for goldfish.

Goldfish bottom sit when they are unwell, stressed, experiencing small tank syndrome, or facing poor water conditions. Bottom sitting is typically accompanied by tightly clamped fins and lethargy. To determine the underlying cause, it is necessary to conduct water tests and look for signs of illness. If a goldfish is unable to swim a distance six times its body length across the tank, it may indicate that the tank is too small.

Goldfish do not sleep during the day when there is light in the surrounding area. If a goldfish is consistently bottom sitting throughout the day, it indicates the presence of other underlying issues that are causing stress to the fish. While some goldfish may sleep on the bottom of the tank, they only do so at night and display loosely down-turned fins during this resting period.

Goldfish bottom-sitting or sleeping?
Goldfish bottom-sitting or sleeping?

Decrease in temperature

Reducing the environmental temperature can encourage goldfish to sleep for longer periods. This is due to the natural association between shorter daylight hours during wintertime. Keeping the water temperature below average for extended periods can lead to your goldfish naturally desiring an earlier sleep schedule. Additionally, lower temperatures can induce decreased activity in goldfish, simulating a sleep-like state.

Goldfish bodily functions during sleep

Even during sleep, goldfish remain capable of passing waste and detecting changes in their environment. Their lateral line, which is sensitive to movements and stimuli, compensates for their poor eyesight in darkness.

During sleep, goldfish exhibit heightened senses, and even the slightest noise or movement can wake them up. They are cautious sleepers and are alert to their owners observing them through the tank, making it challenging to catch them in the act of sleeping.

To accommodate their slowed metabolism during sleep, it is recommended not to feed goldfish a few hours before nightfall, allowing them ample time to digest their previous meal.

When goldfish sleep, their coloration may become dull to blend in with their surroundings. This adaptation is beneficial in the wild as it prevents them from standing out in the darkness. However, their vibrant colors should return when morning comes.

See more:

What Do Goldfish Eat? 10+ Types Of Goldfish Food

Is your fish sick or sleeping?

Understanding the distinction between sleep and rest is crucial to assess the health of your fish. It’s important to be aware that conditions other than swim bladder disorder can be mistaken for a sleeping state.

Although you might assume that your fish is simply taking a nap when it rests near the bottom of the tank, if a goldfish remains in this area for more than twelve hours, it could indicate illness. Monitoring your fish’s behavior and how frequently this occurs is essential.

If your fish remains motionless under light for extended periods, it may be an indication of water-related issues. High levels of ammonia and other nitrates in the tank water can make fish sick and stressed, causing them to appear as though they are sleeping.

Floating near the top or turning over could be signs of a bacterial infection, necessitating a water change.

However, other factors could contribute to this behavior. Inadequate oxygen supply or sleep deprivation could be potential causes. Additionally, improper nutrition from their food could also play a role.

In such cases, your fish may appear pale and motionless. Therefore, it is important to review all aspects of fish care, including oxygenation, sleep quality, and nutrition. If your pet maintains a regular sleep cycle and exhibits regular periods of inactivity, it is likely that they are simply asleep.


In conclusion, the question Do goldfish sleep?” is more intricate than one might assume. While goldfish don’t display traditional signs of sleep like closing their eyes, they do have their unique resting patterns vital for their well-being. It’s essential to differentiate between their natural sleep behavior and signs of distress or illness.

By ensuring a proper light-dark cycle and observing their behavior, you can foster a healthy environment for your goldfish. Here at DryWashAquarium, we’re to delving into such intriguing topics. If you found our exploration enlightening, dive into more enriching articles on our blog! Stay curious and informed with us!

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Mark Senske
Mark Senske
Mark Senske is a highly regarded expert in freshwater and marine aquascaping, specializing in creating captivating and visually striking aquariums. With his extensive knowledge and experience, he excels in designing and maintaining beautiful aquatic environments that showcase the natural beauty of fish and plants.


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