Do Goldfish Sleep?
Goldfish do sleep, though their sleeping patterns look very different from human sleep.
Goldfish are popular pets often kept in aquariums and outdoor ponds. And while they do not have eyelids and cannot close their eyes, goldfish still experience periods of rest and reduced activity.
Here’s what to know about goldfish sleeping behavior and how to recognize it.
Key Takeaways
- Goldfish sleep by becoming less active and hovering in place.
- Goldfish sleep better in dark, quiet environments.
- Lack of sleep can weaken a goldfish’s immune system and metabolism.
- A sideways or upside-down fish is likely sick, not sleeping.
What Do Goldfish Look Like When They Sleep?
Sleeping goldfish become less active and often hover motionless near the bottom of the tank or pond.
Unlike humans, goldfish do not lie down when resting. Instead, they remain upright, hover in place, and move slowly to maintain balance. Sleeping goldfish are typically found low in the water, often an inch or two above the bottom, with their heads slightly pointed downward.
Their color may appear slightly faded while resting and return to normal once awake. This temporary color change may help protect them from predators.
Goldfish also do not experience deep REM sleep, and their brain activity does not change significantly while resting.
When Do Goldfish Sleep?
Goldfish sleep best in dark, quiet environments and often rest at night when aquarium lights are off.
Although goldfish do not follow the same sleep cycle as humans, many become less active at night when their environment becomes darker and quieter.
Keeping a consistent lighting schedule can help encourage goldfish to rest at night and remain active during the day. Aquarium lights should not stay on for more than 12 hours per day, as goldfish require periods of darkness to rest properly.
If the aquarium is too bright, goldfish may hide among plants or decorations to find darker areas for rest. Loud noises and sudden disturbances can also easily startle a resting goldfish awake.
What Happens When Goldfish Don’t Get Enough Sleep?
Goldfish need regular rest to support healthy metabolism, energy levels, and immune function.
Like humans, fish require periods of rest to restore energy and maintain normal body functions. Without enough sleep, goldfish may become more vulnerable to illness and experience reduced activity levels.
Sleep needs can vary between individual fish. Some goldfish may rest periodically during the day, while others remain active until nighttime. Consistent light and dark cycles are important for helping goldfish maintain healthy sleeping patterns.
Although fish may appear to “yawn,” this behavior is not a sign of tiredness. Instead, fish open and close their mouths to move water across their gills for breathing.
How Can You Tell if a Goldfish Is Sleeping or Sick?
Sleeping goldfish typically remain upright and hover calmly, while sick fish may float sideways, upside down, or struggle to swim normally.
Swim bladder disease commonly causes buoyancy problems and abnormal swimming behavior. Floating sideways may also be a sign of bacterial infection or unsafe ammonia or nitrite levels in the water.
If a goldfish is floating sideways or upside down for prolonged periods, contact a veterinarian as soon as possible.
Goldfish that are calmly hovering near the bottom of the tank and appear slightly pale are often simply resting.
Goldfish Sleep FAQs
Do goldfish sleep with their eyes open?
Yes, goldfish sleep with their eyes open because they do not have eyelids.
How can you tell if a goldfish is sleeping?
Sleeping goldfish usually hover in one place, move slowly, and may appear slightly paler in color.
Do goldfish sleep at night?
Goldfish often sleep at night when it is dark and quiet, though they do not follow the same sleep cycle as humans.
Is a sideways goldfish sleeping?
No, a goldfish floating sideways or upside down is usually sick and may need veterinary attention.
