Do Angelfish Sleep

Do Angelfish Sleep? 3 Ways to Tell

Do you ever wonder what your fish are doing when they disappear into the depths of their aquarium for what seems like hours on end? Angelfish, like many other types of fish, do indeed sleep.

But unlike us humans who tend to close our eyes and doze off into a peaceful slumber, fish sleep in a much more subtle way. For the most part, fish remain motionless in their watery homes, resting among the plants or rocks.

This guide will answer your question, do angelfish sleep, and explain everything you need to know about their sleeping habits.

Is It Possible for Fish to Sleep?

Yes, they certainly do! In fact, researchers have found that certain fish species enter into a state of inactivity called torpor, which is very similar to mammalian sleep.

During this time, their brains reduce their metabolic rate, and EEG readings show signs of slowed activity. This indicates that at least some fish can sleep as we do.

However, the way they sleep and the length of time they spend sleeping can vary greatly depending on the species.

Angelfish do not sleep in the same manner as mammals or humans. Instead, they enter into a state of lowered activity where they rest but remain aware of their surroundings.

Here is a youtube guide on whether the fish sleep or not.

Are Angelfish Diurnal or Nocturnal?

Angelfish are nocturnal fish that sleep during the night. When the light begins to fade, you’ll notice them moving toward the bottom of the aquarium and trying to find resting places.

This is essentially what they do in the wild, except that they’ll be resting at various sites. When angelfish are sleeping in the wild, they’ll be hiding among the reef’s many cracks.

How Do Angelfish Sleep?

In the wild, fish will seek out hiding places and nooks to rest. However, if all you have is a tank, your fish will dig through whatever is at the bottom of their water, such as sand, rocks, or live plants.

Others simply hover near the bottom, mostly motionless, with little or no evidence of life. Here are some of the angelfish habits while they are sleeping.

Angelfish Sleep With Their Eyes Open

Interestingly, even though angelfish sleep, they keep their eyes open. They enter into a state of inactive relaxation where they can still see and hear what is happening. This allows them to be alert for any danger that may present itself while they are resting.

Angelfish Slow Down Their Metabolism

When angelfish sleep, they reduce their metabolic rate. This adaptation allows them to conserve energy while they are resting.

Their brain waves also slow down, similar to what happens in humans when we are asleep.

Its blood will travel less rapidly throughout its body, allowing it to digest and breathe. This altered metabolism allows the fish to relax and rejuvenate as needed.

Angelfish Usually Sleep at Night

Once your tank is dark, this indicates that night has fallen, and your fish will want to relax. 

Shallow-water fish such as angelfish would be unable to see in total darkness. For this reason, they are more likely to rest at night.

How Can You Tell That Your Angelfish is Sleeping?

1. Color Change

Angelfish are brightly colored fish with vertical stripes of a darker hue. These bands serve an important purpose by allowing the angelfish to blend in with its surroundings if necessary.

The most interesting part is that angelfish can turn these colors on and off! It looks weird, but yeah, angelfish can do that.

These fish don’t use this on/off mechanism only when trying to hide from a predator or a large fish, but they can also use it when they are trying to sleep.

When you turn your tank’s lights off and let your fish rest, she will go into the bottom of your tank motionless, and its colors will turn off. This is how you can tell that your angelfish is sleeping.

Although certain scientists propose that the fish do this behavior only for physiological purposes, many people believe that the angelfish is sleeping just like we humans do!

2. Angelfish Not Moving

Angelfish are very active fish, and they usually don’t stay still for a long period unless they’re sleeping.

So, if you see your angelfish is not swimming and it’s just resting in one place, then it’s probably sleeping.

3. Sleeping Fish Don’t Attract Other Fish

When one fish sleeps, the others know that it’s time to be quiet. So, if you see that your angelfish is resting and there are no other fish around, it means that the angelfish is resting and not in danger.

Is a Motionless Angelfish Always Asleep?

No, not necessarily. Fish can enter into a state of torpor, or reduced activity, for many reasons.

This could be due to changes in their environment, such as temperature fluctuations or lack of food. It could also be due to stress from being in captivity.

How Does Angelfish Sleep Differ From Human Sleep?

During sleep, we go through many states of unconsciousness. One of these stages is deep sleep, often known as the REM cycle.

However, fish completely do not experience this. When they rest, they do not become unconscious or experience dreams.

An angelfish remains half-awake while sleeping, in other words, it is a light sleeper.

It will utilize this period in the same way as any other creature as its cells will begin to mend and its brain function will improve while it rests.

In addition, angelfish species don’t:

  • Become unaware of their environment
  • Struggle to return to their full energy and alertness when awoken
  • Fail to perceive threats or the arrival of predators

That’s crucial because angelfish are frequently expected to defend their territory and mates.

Also, other angelfish may attack them to establish dominance. So, this light sleeping makes it easier for them to snap to attention when it is needed.

How Do Light Changes Affect Your Fish?

When the light is suddenly switched off, and the angelfish is plunged into unexpected darkness, it may become bewildered.

In the wild, the sun would come up, providing light and warmth, and then slowly set, cooling things off and eventually making it dark.

So, it would help if you replicated this natural light cycle as closely as possible to ensure that your fish are getting the right cues to sleep.

An artificial light source that simulates the sun is ideal, such as a full-spectrum aquarium light. You should also have a timer that turns the light on and off at the same time each day. This will help your angelfish know when to sleep and when it’s time to be active.

Tank lighting
Tank lighting

How Long Do Angelfish Sleep?

There’s currently no scientific evidence on this subject. The inactivity and immobility of an angelfish aren’t in sync when it sleeps.

As a result, determining whether or not it is sleeping is difficult. However, there are certain things we know about a fish’s sleep cycle, including the following:

  • Your angelfish may ‘wake up’ numerous times to check for an activity or fake alarms.
  • They may sleep for a few seconds at a time, waking to inspect their territory or fry before resuming slumber.
  • The angelfish fins may constantly be moving while adjusting their floating position.

Do Angelfish Dream?

According to research in Physiology & Behavior, fish do not dream. While they are at their most peaceful, they don’t enter into a REM cycle or other deeper stages of sleep.

Do Angelfish Sleep Upside Down?

Angelfish do not sleep upside down. If your fish has flipped belly-up, it’s a sign that it’s seriously ill or dead.

The swim bladder of an angelfish stays in excellent form while the fish sleeps. This helps the fish stay upright and balanced while immersed in water.

When the fish dies or loses its swim bladder due to an infection, this changes, and the fish may flip over.

Upside down angelfish

Do Angelfish Move When Sleeping?

Even a sleeping fish will make tiny adjustments in its position. This is intended to correct the course of the fish as it floats and keep water flowing over its gills.

By doing this, they can control how much water flows over their gills and guarantee that they’re getting enough oxygen.

In addition, the angelfish may:

  • Twitch its fins slightly
  • Flick its tail once or twice

Likewise, you may notice your angelfish suddenly moving when you turn on the lights. This happens because your fish is startled out of its sleep.

Do Migrating Fish Sleep?

When fish migrate, you can see that they swim continuously for lengthy periods. Does this imply that they don’t sleep? Well, they do.

As previously said, when fish are sleeping, they can continue to move.

The cool fact that migratory fish are swimming in a school implies they reduced their need for visual sensory information.

As a result, they may fall asleep and continue to swim alongside the other fish with reduced vision.

Migration in fishes - Online Biology Notes
Fish Migrating by onlinebiologynotes

What Do Angelfish Need To Sleep? 

When your angelfish is tired enough, it will sleep. However, this might not be easy if its tank settings aren’t set to the fish’s ideal range.

The fish will become stressed and unwilling to sleep because it thinks there is danger present.

It would help if you did the following things for your fish to relax properly:


Why Do Angelfish Keep Moving Even When They Are Sleeping?

As previously stated, fish do not sleep in the same way as humans. They do not usually remain in one area throughout the night.

And because water must be circulating over their gills to ensure that their bodies are oxygenated.

The fish will continue swimming even when they sleep, though they move much more slowly.

How Do I Know If My Angelfish Is Sleeping?

There are several ways to tell if your angelfish is sleeping:

  • The fish’s eyes will be open.
  • The fish may be floating near the surface or at the bottom of the tank.
  • The fish may be still or make slight movements.
  • The fish’s gills will continue to move and it will take in oxygen.

Can I Wake Up My Angelfish When It’s Sleeping?

You can, but I don’t recommend that. It’s best to leave your fish to sleep undisturbed. However, if you have to wake it, do so slowly and carefully so as not to startle the fish.

What Happens If My Angelfish Is Disturbed While Sleeping?

If your fish is disturbed while sleeping, it may be startled and swim away quickly. This isn’t harmful to the fish, but it can be disruptive to its sleep cycle.

What Are the Benefits of Sleeping for Angelfish?

During sleep, cells in the body mend, and brain function improves. So, angelfish need to sleep in order to stay healthy.

In addition, fish that are well-rested are less likely to be stressed, which makes them less susceptible to disease.

Last Words

All animals sleep and angelfish are no exception. However, their sleep habits may differ from those of other animals.

We hope this article has answered all of your questions about angelfish sleep. Please feel free to leave a comment if you have any other inquiries.