How Do Goldfish Sleep?

Goldfish seem to swim endlessly around the fishbowl without sleeping. Yet, goldfish still need rest. 

Goldfish become stressed out when they do not get enough rest. So, how do goldfish sleep?

Goldfish rest by becoming less active. They simply float in the water while moving slowly to keep themselves upright. As with many animal species, goldfish sleep in short bursts. However, goldfish can get up to 12 hours of rest per day.

Here is what you should know about how goldfish sleep.

Goldfish Hover In The Water During Rest

Goldfish sleep by hovering in the water. They often float near the bottom of the tank or pond with their heads pointed slightly down. 

Sleeping goldfish also appear motionless. They do not move their fins or body, which makes them appear to float in the water. 

The color of the goldfish also fades slightly during rest. Instead of bright orange, white, or black, the goldfish’s scales appear muted. The faded color of the goldfish is a defense mechanism. It helps the fish blend in with its surroundings to help them hide from predators.

Yet, the color of a goldfish can change for a variety of reasons. Goldfish have pigment in their skin. The pigment loses color without exposure to sunlight. The color may also fade due to colder water, old age, or stress. 

Goldfish sleep most of the night and take naps throughout the day, but they do not close their eyes and enter deep sleep. Goldfish enter periods of light sleep or rest that allow them to conserve energy.

Unlike humans, the goldfish’s brain waves do not change during rest. The fish remains aware of its surroundings, allowing it to quickly dart away from danger.

Goldfish Sleep In Dark And Quiet Environments

Household goldfish tend to follow the same sleep schedule as humans, as they prefer to sleep when it is dark and quiet. If you turn off the lights at night and make no noise, the fish are likely to sleep through the night.

Goldfish may seek shelter in the tank if the environment is not dark enough. For example, if lights are still on in the room, goldfish may swim under plants or tank structures to escape the light.

Many aquarists use timers to control the day/night cycle for their fish tanks. Maintaining a consistent schedule makes it easier for goldfish to get adequate sleep. 

Goldfish do not fall asleep instantly. They gradually enter a state of light rest. It takes between 15 and 60 minutes for a goldfish to enter its sleep state. Before sleeping, the goldfish starts moving less and eating less. It slowly becomes less active until it finally achieves sleep.

Goldfish Sometimes Sleep In Groups

Goldfish sleep when they are comfortable and secure, which is why they often prefer to sleep in groups. If you have multiple goldfish in a tank or pond, you may notice that pairs of goldfish sleep at the same time.

Goldfish are social animals but also spend most of their time exploring the water on their own. When it comes time for rest, they may find another fish and prepare for sleep. 

Goldfish Are Light Sleepers 

Goldfish go through periods of rest but remain mostly aware of their surroundings. Any change to their environment is likely to wake them from their rest. 

The sound of footsteps approaching a fish tank, a light turning on in the room, or any other disturbance is likely to startle the fish awake. Frequently startling a goldfish creates stress, which impacts its health. Goldfish that suffer from too much stress may eat less and become more vulnerable to various illnesses.

Do Goldfish Need to Sleep?

Goldfish do not sleep with their eyes closed, but rest is still very important for their health. Sleeping helps goldfish restore their energy and keep their immune system functioning properly. 

Goldfish that do not get enough sleep are more susceptible to diseases and illnesses. Their metabolism slows, which limits the function of the immune system and makes them more vulnerable to bacterial and fungal infections.

Goldfish owners may detect signs that their fish need more sleep. Goldfish that lack sleep may continue to swim throughout the night and spend more time during the day seeking hiding spots for short naps. 

Limiting food intake may help sleep-deprived goldfish get more rest. Overeating leaves the goldfish with excess energy, which makes it more difficult for them to sleep.

Do Goldfish Sleep On Their Sides Or Upside Down?

Goldfish may occasionally lilt forward with their head lower than the tail. However, goldfish do not frequently sleep on their sides or upside down. They typically rest upright as they float in the water. 

A goldfish that is on its side or upside down is likely suffering from an illness, such as swim bladder disease. However, goldfish in a deep tank may occasionally tilt to their sides for several minutes when resting. They gradually float toward the surface and drift back to the bottom of the tank.

Do Goldfish Dream When They Sleep?

Scientists do not believe that goldfish dream. Animals that dream must enter deep sleep. For example, humans and many other mammals enter a state of sleep called rapid eye movement (REM) sleep. During REM sleep, your brain activity increases as you dream. 

A goldfish’s brain activity remains the same during rest. They do not enter deep sleep and most likely do not dream. 

Conclusion

Goldfish need rest to stay healthy. However, instead of closing their eyes, they simply become less active. They spend up to 12 hours per day in an inactive state. 

A sleeping goldfish may lower its head and seem to float near the bottom of the tank or pond. They do not move their fins or tail. Their coloring also fades slightly. These changes allow the fish to conserve energy.

Yet, if the goldfish is leaning to its side as it floats, it is likely suffering from an illness or disease. Goldfish do not sleep sideways or upside down.