Do Molly Fish Sleep?

If you are a fish-keeper, and you wonder if molly fish sleep, this article is just the right source of information for you.

So, do molly fish sleep? Yes, molly fish sleep like most fish do. However, as an aquarist, you need to be certain that your fish is getting the rest he needs. So we recommend that you dim the aquarium light at night.

Truly, scientists have not determined if all animals. But, not only do you need to know if molly fish sleep or not, but this article will also reveal how, when, and where they sleep.

How Do Molly Fish Sleep?

Like other fish, molly fish lacks eyelids. So, they look for a cozy environment to rest. Also, they do not close their eyes, and they remain in motion while at rest.

However, many mollies species continue in motion, and they hardly close their eyes. Moreover, they move frequently to enable oxygen flow into their gills. Also, they do this by moving their fins occasionally.

Sometimes, fish owners get to know if fish are asleep by observing their movement. However, mollies tend to move slowly, and they often move toward the deep part at the surface. Also, if your fish are moving below their normal elevation, you can be sure they are trying to get a rest.

Although, most species of molly fish rather stay awake in the day than night. However, some species can be categorized as “nocturnal”. Since they stay alert during the night and they don’t sleep like the rest. However, these “nocturnal” species still find a hiding place that is far away from predators in the evening.

Unlike humans, fish easily adjust their sleeping pattern to migration patterns, new parenthood, food availability, and water temperature, as they do not follow circadian rhythm strictly.

Why Do Molly Fish Sleep?

Just as humans, fish also need rest for proper body functioning. Although, molly fish do not completely shut their eye, due to the absence of eyelids. But having their mind in a state of rest does good to them.

Moreover, sleeping moment is a time for rejuvenation, repair, forming memories, and processing information. However, there is a difference in the activity that goes on in their sleep when compared to humans.

Apart from the partial movement that occur in molly fish, they don’t undergo the dreaming stage in their sleep. This is due to the fact that their brain isn’t as complex as that of humans.

Moreover, the dreaming stage of sleep is usually referred to as REM, meaning, rapid eye movement.

What Does a Sleeping Molly Fish Looks Like?

For most mollies, their sleeping state usually appear as though they are in a day dreaming position. Moreover, some species nestle into the bottom part of the water body they live in, while other species just hover around the bottom, without getting too close to it.

Moreover, some sleeping molly fish appear to be immobile, except the steady movement of their fins. Also, some species can be so deeply asleep, that they won’t be aware if they are being carried out of the water.

How Long Does a Molly Fish Sleep?

The amount of time a molly get to sleep is not definite. As, it depends on environmental condition, and how active they were throughout the day.

However, for molly fish that are kept in aquarium, interior light is the major determinant of their sleep cycle. Moreover, they sleep better when you turn the light off.

Can Molly Fish Have a Sleeping Disorder?

Firstly, molly fish do not follow a regular sleeping pattern, especially when the females just give birth, or during moments like spawning or migration. When molly fish migrate to a different environment, the first thing is them adjusting to the new environment condition. Meanwhile, this may have an effect on their previous sleeping pattern.

Moreover, just few fish can suffer from sleep deprivation or sleep disorders. Also, some fish can have a condition called insomnia, which is the inability to drift off and sleep as long as they normally do.

However, they later get back to their previous state easily. That is, they go back to their previous sleeping pattern, under normal conditions. However, it is not widely observed if molly fish can experience insomnia.

Related Questions

A lot of questions are frequently asked about the sleeping nature of molly fish. Fortunately, this article has answered this question, but there are other questions that may be in the mind of readers, which answers are also provided to;

Do Molly Fish Sleep Upside Down?

Molly fish do not sleep upside down on a normal condition. However, in case you see your fish sleeping in this position, you should check the health condition of your fish. As something may be wrong with it.

However, some mollies species with a round tummy may exhibit this behavior. But in most cases, if a fish is sleeping upside down, it can be related to swim bladder disease, which result to them not being able to balance their weight, or control their movement.

Do Molly Fish Have Eyelids?

Generally, most fish do not have eyelids. So, molly fish also lacks one. Although, sharks are exception to this. But then, the eyelid sharks have is not the same as that of humans. However, it appears like a membrane i.e., a covering. But it performs similar function.

Why Do Molly Fish Sleep with Their Eyes Open?

It understandable that it can be kind of creepy to watch your fish sleep with his eyes open. Nevertheless, you don’t have to be scared of losing your fish.

However, with the absence of eyelids, they have no choice but to leave their eyes open while asleep, since they have no eyelid they can use to shut their eyes.

What Are the Sleeping Habits of Betta Fish?

Betta fish are beautiful creatures that are known as frequent nappers. This is because they often take time to find a secured and cozy place to rest. Usually, they rest among plant structures, leaves, filter, or tank ornaments.

Also, betta rest mostly at night. So you should provide a means for switching on and off their tank light. Moreover, if you are keeping a betta fish, ensure you provide plenty resting and hiding space for them.

However, some fish such as whales and dolphins, have a kind of different sleeping condition. While they sleep, one hemisphere of their brain is usually at rest at a time. Moreover, the brain is mostly awake throughout their sleep period.


As stated earlier about the sleeping habit of molly fish, you would observe that they exhibit some traits similar to that of humans, in their natural environment.

However, you have to study molly fish well, in order not to mix a disease symptom with their sleeping habit. Be at alert to recognize any change in your fish wellbeing, in order to determine if there is a need for treatment.