Do Angelfish Sleep?

Like many fish species, angelfish do sleep, at least in so far as sleep is determined for a fish. Unlike humans and other land animals in whom sleeping is obvious through physical immobility, fish will still have a small range of mobility as they sway in the current resting.

We will look at when, where, and how angelfish sleep, what happens when your angelfish don’t get enough rest, and how you can help your angelfish get enough sleep.

Do Angelfish Sleep?

Angelfish are very much like any other animal ad do need to rest. Sleeping in fish is not as apparent as it appears for land animals. Due to this, there is a perception that fish don’t sleep; this, however, is not true.

Fish need sleep, but their way of sleeping looks very different as they spend their lives underwater. Because of this, they will often seem to be moving due to the current and thus look awake.

As fish breathe through their gills, requiring a constant flow of water, they will always maintain a small amount of movement, even at rest and when sleeping.

In addition to this minimal movement, angelfish sleep with their eyes open. Unlike land animals whose eyes will dry out, angelfish and many other fish don’t need to close their eyes to sleep as they are surrounded by water.

Striped Angelfish with Plants on Sand

When Do Angelfish Sleep?

Angelfish are diurnal animals, which means they are active during the day and will rest and sleep during the night. Because of this, the amount of light exposed to an angelfish may affect their sleep.

Does Light Affect How Angelfish Sleep?

Light can affect the sleep patterns of angelfish. Because they are diurnal, they are programmed to rest when it is dark and become active when it is light.

If you have a bright tank light on all the time, your angelfish may become confused.

Constant light will be detrimental to the angelfish’s natural sleep patterns. If you have a tank light, be sure to dim it at night so that your angelfish can get adequate sleep.

Like other animals, sleep is an important facet of good health, and an angelfish needs enough sleep to be healthy and energized.

Where Do Angelfish Sleep?

Angelfish will generally be found sleeping near the floor of their tank or towards the bottom of their tank.

They prefer slow-moving water, and the tank floor is usually furthest from the pump inlet, allowing them to relax out of the current flow.

That said, be sure to keep an eye on your angelfish, as although many angelfish do prefer napping near the floor of the tank, this could also be a sign of a problematic swim bladder.

If the fish shows no signs of moving to different areas of the tank when awake, it is best to consult a vet.

How To Tell That An Angelfish Is Sleeping?

At first glance, as with many fish, it is not obvious that an angelfish is sleeping, but there are a few telltale signs that you can look out for:

  • Angelfish are generally active fish and move about their tank quite often when awake. If the angelfish is relatively immobile and remains in one corner of a tank, it is likely resting.
  • A further sign is if the angelfish is resting near the bottom of the tank.
  • Another sleep indicator, and quite an interesting one, is that you may notice a slight color difference in your angelfish. Sleep is not always the only factor that causes a color change, but when at rest, an angelfish may look faded; once the angelfish is awake, the colors should revive.

Do Angelfish Sleep Upside Down?

Angelfish do not sleep upside down. This is another common but false belief. If you see a fish upside down, it is best to take it straight to the vet. This is also true of fish that swim on their sides.

Angelfish will sleep lying horizontally in the same manner that they will usually swim; if your angelfish is lying on its side or upside down, please consult a vet immediately.

What Happens If Angelfish Don’t Get Enough Sleep?

Sleep is very important for all animals, and it is a time when the body can rest and regenerate in preparation for wakeful living. We all know how horrible we feel when we lack enough sleep.

Lack of sleep can lead to lethargy, irritability, confusion, and illness as the body struggles to function adequately. The same applies to angelfish; a lack of sleep can be detrimental to an angelfish’s overall well-being.

What Are The Signs An Angelfish Isn’t Sleeping?

While the following signs may apply to lack of sleep, it is important to note that they may also denote other problems. It is best practice as a fish owner to talk to a veterinarian whenever your fish shows unusual behavior or symptoms:


If an angelfish is showing very slow, sluggish behavior, this may be a symptom of a lack of sleep. As always, check with your vet.


Although illness may have many causes, lack of sleep can lead to ill-health due to the stress no sleep can have on the fish.

How To Help Angelfish Get Enough Sleep

We all know we sleep best in comfortable conditions. These are some factors you can consider when helping your angelfish have the best conditions to sleep in:


As we have discussed, angelfish are diurnal, so they will feel comfortable sleeping if their tanks are brightly lit up all the time. To help them sleep, make sure that they get to experience both daylight and night hours.

If you use a tank light at night, make sure it won’t emit light that will disturb your angelfish and sleep.


Angelfish are tropical fish and need warmer water for comfort, ensure that your tank temperature stays steady at around 80° F.


No one likes to sleep in a dirty bed; make sure your tank is clean and well-oxygenated, angelfish like softer, slightly acid water with a pH of 6.5.


Angelfish do spend time sleeping. Their most likely sleeping hours are during the night as they are diurnal and will be more active during the day. When sleeping, angelfish are often found near the bottom of a tank with little movement.