Do Catfish Sleep and Why Would they Sleep?

Catfish sleep, like humans, and they also need to rest and recharge their bodies. Yes, all the catfish don’t sleep at the same time, but they do need to take a rest. Unlike blind cavefish that cannot distinguish between day and night and so do not need sleep, catfish still need sleep. You would not be able to tell if a catfish was asleep, because they don’t have eyelids, like humans.

Catfish in dark

How does catfish sleep?

Of course, fish need sleep as well to rest. However, the way that fish sleeps is much different than that of humans. You can’t even tell if the fish is sleeping or not like humans.

The thing is sleep means different things to different organisms. Since fish don’t have eyelids because there is no dust underwater, they seem to be awake even when sleeping. In fish, sleeping means resting so you can again be active later. This may be observed when the fish stays very still in an aquarium, such as catfish. Many fish can stay without sleep for a while as well, so unlike people, it is not an absolute necessity for them.

For fish, sleeping doesn’t really mean resting completely but simply becoming less aware of the surroundings. This means that they are half-awake even when sleeping so they can be ready in case of predators around them. Catfish are known to rest in small crevices and behind logs so that they are not ambushed while resting.

These catfish are actually pretty deep sleepers compared to other species of fish. You will not be able to tell that it is sleeping, but if the fish is hiding, it is probably resting.

Sleeping behavior of catfish

There are many species of catfish in the world. Some live in saltwater, some in freshwater, and some in brackish water. Due to these various living environments, they have developed sleeping behaviors that best fit their surroundings. Some catfish are nocturnal, while others are diurnal, so they have different periods when they rest. There is also a less known group of catfish known as crepuscular. Here is the difference between these three types of sleeping behavior of catfish.

Nocturnal catfish

Nocturnal catfish need to be active during the night and usually rest during the day. These fish hunt for food at night, which means when it is dark and not during the day with light. These fish might not sleep during the day, but they will definitely be less active in the light. These fish rely on the darkness to hunt for food in the water.

Diurnal catfish

These catfish are more like humans as they rest during the night and are active during the day when there is light. Most catfish are diurnal as they are able to look at the prey better in the light. At night, they hide in crevices and holes to hide and rest for the night. Diurnal catfish are easier to care for as they do not need artificial lightning and can follow the natural light and progress of the day.

Crepuscular catfish

These catfish are much rarer. In this, the fish are active only during the dawn and dusk, the times when humans are just awakening or winding down. These peculiar fish have a unique time frame for being active, so it is difficult to recreate their natural habitat in the tank. This sleeping pattern allows them to encounter more fish to prey on as other fish are also just waking up or going to sleep.

Why do catfish sleep?

Since fish don’t need to work like humans or function like us, you might wonder why they need sleep. Moreover, the sleeping behavior of fish is very strange as they are either half-sleep or just resting, so sleep doesn’t serve exactly the same purpose as in humans.

Interestingly, it is still speculation as to why fish need sleep, but there are two theories as to why catfish sleep, which are mentioned below.

To restore energy

Although catfish might not work like humans, they do work in their own way. Most catfish are omnivorous, which means they have to hunt for food, and that requires energy. Sleeping helps them restore this energy lost and repair their cells like us.

Just like humans, fish are also made up of cells, so tissue repairs, muscles grow, and protein synthesis occurs only when they are resting. Their sleep might not be as deep as ours, but it is still important for their health and to prevent diseases. Sleep also allows one to be more alert and process new information. Of course, these things don’t happen in fish like humans, but to some degree, they do occur.

How brain development causes a difference in a fish sleep versus a human

A fish brain is different from a human’s brain because of the neocortex we possess in relation to the other two parts. There is no neocortex in fish, and the neocortex in humans is responsible for many functions and is one of the reasons humans’ sleep. During sleep the short-term memories for humans can be “moved” to long-term memories. Without a neocortex the process of sleep operates differently for other animals, and this is one reason why a fish does not sleep in the same manner. The potential for predation of them has caused a difference in brain development and thus sleep patterns. 

To protect themselves

Catfish can’t swim around forever; they will eventually die. Swimming requires energy, and this period of rest helps them conserve energy. When the fish emerges again, it is much more active and ready to attack prey. Moreover, they only rest when they know that there is not much food around them.

In addition to that, when the fish is hiding and sleeping, it can avoid predators. Catfish usually hide when asleep, so during this time, a big fish or alligator cannot find them, and thus, it protects them from outside predators. This makes sleep an adaptative and protective function.


Basically, catfish do sleep, and in fact, it is pretty important for them as well. Some catfish are nocturnal, so they sleep during the day, while others are diurnal and they sleep at night. The third catfish group is called crepuscular, but it is very rare.

The catfish need sleep to rest, restore energy, and protect themselves from predators. It is not absolutely necessary for fish to sleep, but it is important for them if they want to conserve energy.

Leave a Comment

Your email address will not be published. Required fields are marked *