There are several species of fish that are observed really sleeping. So the answer for  “DO FISH SLEEP” is YES without any doubts.

The researchers still struggle to define what sleep really is, and why so many species need to sleep. A commonly used definition for sleep is that; animals are accepted as sleeping, if they regularly rest in a certain position and simultaneously reacts less to sensory stimuli, such as light, sound, electricity and pressure.

In the light of this definition, the researchers found examples of sleepers in virtually all animal groups – even in bees and wasps.

Biologists knowledge of the sleep habits of the fish are, however, quite limited – for example, they are not sure  if any fish species need to sleep.

How Do Fish Sleep? Which Fish Species are Observed Sleeping?

Do Fish Sleep in the concept of humans? Or their slowed motions give us the idea that they are just sleeping other than resting.

The zebrafish is showing clear signs of sleep

Do Zebra Fish Sleep or just Rest?

The Zebra Fish, show clear signs of sleeping and is frequently used in sleep research. Both larvae and  adult Zebra Fish goes  into sleep states; where they show less reaction to sensory inputs. When larvae are sleeping, keep the head down while the adult fish sleep revealed opposite behavior.

When it’s bedtime, the most dormant species just go towards the bottom without any other special preparations.


Blind fish do not sleep

 how do blind fish sleep?

Fish that live in dark caves or born blind (eg the Mexican Typhliasina pearsei ), shows no sign of sleep behavior.

Scientists believe that these species do not need sleep. They are not stimulated visually, and therefore their brains doesn’t react on those kind of stimulus.

Shoal Fish have similarly less need for sleep, Because they  just concentrate on following the closest fish in the shoal and therefore use their sense of vision significantly smaller than fish that do not live in shoals.


Parrot fish do sleep in a slime balloon

Do fish sleep? Yes Parrot fish do sleep.

Parrot fish has an exceptional talent. Parrot fish lies down to sleep in the coral reef, secrete a mucous bag through the mouth. After half an hour the slime bag encloses  the whole body, and parrot fish settles in its secure balloon. This Mucus balloon  probably hides its smell to predators and thus provides Parrot Fish with a safe heaven.


1. The brain processes sensory information and regulates the memory.

2. The hormones are regulated.

3. The body’s immune system is strengthened.

4. Damaged cells repaired.

5. The body saves energy.