Of course fish sleep! It is true that fish don't sleep in the same way humans do .However, since they lack eyelids, they cannot close their eyes. This makes it difficult to tell if they are actually sleeping.dioxide. Therefore, they need to keep swimming constantly to create a flow of water over their gills and maintain respiration.
Fish sleep in a variety of ways:
・Some fish sleep while swimming.
・Others sleep on the bottom of the tank or ocean.
・Some fish even sleep upside down!
・The amount of sleep that fish need varies depending on the species.
Therefore, it's more accurate to say that fish undergo periods of rest rather than true sleep as humans understand it.
Here are some interesting examples of how fish "sleep"
Sharks: Sharks must constantly swim to keep water flowing over their gills. They "sleep" while swimming slowly near the surface or by resting on the bottom of the ocean.
Goldfish: Goldfish have been observed to "sleep" in short bursts throughout the day, often resting on the bottom of their tank.
Octopus: Octopus have two large brains and two smaller optic lobes. They "sleep" with one brain hemisphere at a time, allowing them to stay partially alert even while resting.
Eels: Eels bury themselves in mud or sand to "sleep".
It is thought that fish that always swim, such as tuna and mackerel, rest their bodies by swimming slowly at night.
