Do Molly Fish Sleep?

Do Molly Fish Sleep?

Sometimes we stare at our Molly Fish and wonder if they ever fall asleep. We watch them moving around the tank and assume that they are always active. So, do Molly Fish Sleep?

Actually, Molly Fish sleep. They have a diurnal rhythm, which means they need the lights to be off for 12 hours each night during sleep cycles.

In this guide, we’ll go through everything you need to know about Molly Fish’s sleeping patterns, and cycles, and also, we will tell you how to help your Molly Fish have a restful night’s sleep.

What Is the Sleeping Behavior of Molly Fish?

It’s sometimes difficult to distinguish between a fish that is sleeping and one that is merely uninterested, sluggish, or even ill.

The following symptoms will let you know whether or not your molly fish is in good health and sleeping well:

1. Remain Upright

When a molly fish is sleeping, it will remain in an upright position. It will not lie on its side or upside down.

Otherwise, if your molly fish is listing to one side or another, this is a sign of illness and you should seek professional help.

2. Gills Flutter Slowly

The gills of a molly fish flutter slowly when it’s sleeping. If the gills move quickly, this may be a sign of respiratory distress and the molly fish is not getting enough oxygen.

3. Breathe Slowly

When a molly fish is asleep, you will notice that it breathes slowly through its gills. The fish’s mouth may also be slightly open during this time.

4. Hovering above the Substrate

If you see your molly fish hovering a few inches above the substrate, they will be probably sleeping. However, if the molly is close to the substrate and not moving, this may be a sign of illness.

5. Move Their Fins Slowly

To maintain an upright position, molly fish move their fins slightly. The water keeps moving and your molly fish shift forward or backward, allowing oxygen to enter the gills.

6. Little or No Movement of the Mouth or Eyes

Molly fish will have little or no movement of the mouth and eyes during sleep. The fish’s body is still and only the fins move slightly.

Also, the molly fish’s eyes will be open during this time.

7. Revived or Active Once the Lights Turn on

Molly fish usually sleep at night when the lights are off in the aquarium. However, they may also take a nap during the day.

If you turn on the lights in the aquarium and your molly fish is revived or active, this is a good sign that it was only sleeping.

Otherwise, if the molly fish does not move or react to the light, this may be a sign that the fish is dying.

Why Do Molly Fish Sleep?

Like humans and other animals, molly fish need rest. Sleep aids your molly fish in the following ways:

1. Repair and Rebuild

During sleep your molly fish’s body repairs and rebuilds tissues. This helps to keep the fish healthy and free from disease which will also help the molly fish to grow.

2. Boosts the Immune System

Sleep also helps to boost the immune system, making your molly fish less likely to get sick. Therefore, if your molly fish does get sick, it will be able to fight off the illness more easily.

3. Increases Energy Levels

Since molly fish are active during the day, they need to sleep at night to restore their energy levels.

So after a good night’s sleep, your molly fish will have more energy to swim around and explore its surroundings.

4. Reduces Stress

Proper sleep also reduces stress in molly fish. This is because when a molly fish is stressed, its body releases stress hormones that can be harmful to the fish.

By getting enough sleep, your molly fish will be able to reduce the number of stress hormones in its body and stay healthy.

5. Strengthen Organs and Tissues

During sleep, the blood flow to the organs and tissues of your molly fish increases. This helps to strengthen these organs and tissues.

What Are the Tank’s Regions Where Mollis Sleep?

Molly fish sleep in various regions in the tank. For instance, some sleep in the middle of the tank while others choose to stay near the bottom or at the top.

Here are some of the most common regions where Mollies sleep:

1. In the Bottom of the Tank

Molly Fish that sleep in the bottom of the tank choose this area because it provides them with a sense of security. Additionally, the substrate at the bottom of the tank can help to keep their bodies cool.

2. In the Middle of the Tank

Although molly fish may be found resting in the middle of the tank, this location is not as safe as the bottom.

However, they rest in the middle of the tank to avoid sharing spaces with other fish while they sleep since they don’t want anybody else jumping on them and disturbing their slumber.

3. At the Side

Mollies can also sleep at the side of their aquarium. When they are sleeping, they will either lie down along a wall or float from one end of the tank to the other.

As mollies find it more comfortable to sleep in places with less activity and movement.

4. In a Plant

Molly Fish may choose to sleep in a plant to have some peace and quite time while resting.

Therefore, molly fish would select a plant to rest undisturbed by external influences such as light and loud noises.

Can Molly Fish Have a Sleeping Disorder?

There are times when your molly fish may have issues getting the amount of sleep they require to keep their bodies functioning properly and living full lives.

The following cases illustrate that molly fish are not getting the amount of rest they require:

1. Females Who Give Birth

Pregnant females may not be able to get enough sleep because they have to take care of their fry. Additionally, the process of giving birth can be stressful and tiring for them.

2. Sick Molly Fish

Molly fish that are sick or injured may also have trouble sleeping. This is because their bodies are working overtime to heal themselves, which can be exhausting.

3. New Molly Fish in the Tank

When you add new molly fish to your tank, they may not be able to sleep well because they are trying to adjust to their new surroundings.

Also, they may be bullied by the other fish in the tank, which can cause them a lot of stress.

4. Poor Water Conditions

If the water conditions in your tank are not ideal, your molly fish may have trouble sleeping. Since they are constantly trying to stay afloat and avoid getting sick.

For example, if the water is too hot or cold, it can be difficult for them to regulate their body temperature, which can lead to sleep deprivation.

5. loud Noises

If there is a lot of noise in your home, it can also keep your molly fish up at night. As mollies are sensitive to sound and need a quiet environment to sleep well.

5. Bright Lighting

Too much light can also cause molly fish to have difficulty sleeping.

As mentioned before, mollies prefer to sleep in dark and quiet places. So, if the tank is too bright, it can be disruptive to their sleep patterns.

6. Moments of Spawning

Males and females molly fish can also have trouble sleeping when they are spawning.

During the spawning period, they are constantly chasing each other around and trying to find the perfect spot to lay their eggs. This can be quite tiring and leave them little time to rest.

7. Migration in the Wild

Molly fish that live in the wild may also have trouble sleeping when they are migrating. Since they have to travel long distances, they can get very tired and may not be able to find a place to rest.

8. Unsuitable Tankmates

If your molly fish are not compatible with their tankmates, they may have trouble sleeping.

Housing your mollies with aggressive tankmates will lead to a lot of fighting, which can be stressful and prevent them from getting a good night’s sleep.

9. Overcrowded Tanks

Overcrowded tanks can also cause molly fish to have difficulty sleeping, since mollies do not like to feel cramped while resting.

Furthermore, a small tank will lead to aggression and fighting among the fish as they try to establish their territory, making them even more stressed and preventing them from sleeping.

10. Poor Diet

Lack of nutrition will lead to your molly fish not being able to sleep. As their bodies are not getting the sustenance they need to function properly.

11. Tank Is Too Small

12. Lack of Hiding Places

If there are not enough hiding places in the tank, the molly fish may feel exposed and vulnerable. This can lead to stress and insomnia.

How to Help Molly Fish to Sleep Well?

As mentioned before, proper sleep is essential for the good health of your molly fish. If they are not able to get enough rest, it can lead to several health problems.

Therefore, it is important to provide them with the conditions they need to sleep well. The following are some tips on how to do this:

1. Create a Quiet Environment

They must have a peaceful environment with little to no movement in the water, and they can spend time there without being afraid of predators or other tankmates.

Keep the tank’s environment peaceful and quiet by avoiding making noise around it or playing music loudly. Mollies are susceptible to sound.

2. Provide them with Plenty of Hiding Places

Molly Fish require plants and locations where they can conceal themselves from light at night, therefore it’s ideal to provide them hiding places.

In addition, avoid sharp objects in the tank as they can hurt the fish when they’re trying to sleep.

3. Keep the Tank’s Water Conditions Stable

It’s important to maintain stable water conditions in the tank as mollies are very sensitive to changes in temperature (72-78 Fahrenheit) and pH levels (7.5-8.5).

Therefore, make sure to do regular water changes and test the water regularly to ensure that the conditions are ideal for them.

Furthermore, provide them with a filter and aerator to keep the water clean and oxygenated.

4. Give Them a Good Diet

A healthy diet is essential for molly fish to sleep well. Make sure to give them a varied diet that includes all the nutrients they need.

Also, avoid overfeeding them as this can lead to health problems.

You should also avoid feeding Mollies for at least two hours before going to sleep, as this might cause stomach issues and prevent them from sleeping.

5. Use a Soft Light

They require at least 12 hours of darkness every day, so you should cover or turn off your tank lights during their sleep time.

You can use a soft red LED light to help them sleep, as this color has a calming effect on fish.

6. Provide Suitable Tankmates

Compatible tank mates are important for molly fish to sleep well. Avoid putting them with fish that are aggressive or larger than them.

Peaceful tankmates will make them feel more secure and allow them to sleep better.

7. Avoid Overcrowding

As mentioned before, overcrowding can lead to aggression and stress among fish, preventing them from sleeping.

Therefore, it’s important to provide them with enough space to move around and establish their territory.

8. Acclimitaing New Fish

When adding new fish to the tank, it’s important to acclimate them properly to avoid shocking the mollies and causing them stress.

The floating technique is an option. You fill a bag with water from their tank and float the new fish in molly’s tank for 15 minutes. After 15 minutes, you can release the new fish into the tank.

What Is the Sleeping Cycle of Molly Fish?

Molly Fish have a diurnal sleep cycle, which means that they are most active during the day and sleep at night.

During their sleep, Molly Fish enter a state of reduced activity and metabolism. Their brain activity also decreases during this time.

How Much Sleep Do Molly Fish Need?

They require around 12 hours of rest each day. However, some research claims that they can survive on six hours of sleep per night if their environment has a fixed temperature and water condition.

Mollies normally sleep at night, which may range from dusk to dawn. Therefore, they need a secure and safe location with enough area for their habitat so that they are not injured while sleeping.

Do Molly Fish Sleep Upside Down?

Molly fish do not sleep upside down. If you notice that your molly fish is sleeping upside down or to its side, there might be a problem with buoyancy due to swim bladder illness.

It’s possible that your molly fish is leaning on its side or upside down because of constipation or bloating, which is pushing against the swim bladder and forcing it to lean on its side or upside down.


Do Molly Fish Jump out of the Tank?

Mollies usually jump out of the tank if they feel threatened. So it is important to add a tank lid to prevent Molly Fish from jumping out of the tank and getting hurt.

How Long Do Molly Fish Live?

Mollies can live for up to two to five years when properly cared for. Typically, their lifespan is determined by a variety of factors including tank size, water quality, and food.

What Is the Molly Fish Maximum Size?

The maximum length molly fish can reach is approximately four inches. However, they generally grow between two and four inches in length.

Do Molly Fish Eat When They Are Sleeping?

Mollies do not eat while sleeping. Instead, mollies only breathe when they sleep because of an organ known as the labyrinth organ.

Do Molly Fish Have Eyelids?

The majority of aquatic animals do not have eyelids, and molly fish are among them. However, mollies do have a nictitating membrane, which is a clear layer that covers and protects the eye.

Last Words

Molly fish require proper sleep to stay healthy and function properly. By providing them with a dark and quiet environment, you can help them sleep better.

In addition, compatible tank mates and enough space are important for mollies to reduce stress and sleep well. 

We hope this article was helpful and informative. If you have any questions or would like to share your experiences, please leave a comment below.

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