There are many kinds of fish, so there is no fixed answer to sleep a few hours a day, generally only 2-3 hours short, a little longer up to 5 hours. Because there is no safe place to hide in the water, their sleep time is not long, and a little fluctuation can cause them to wake up, so as to better avoid the invasion of natural enemies and other organisms.
1. Hide and sleep: Generally, fish sleep by hiding, such as carp, crucian carp, etc. They will hide near water plants or stones, so as to avoid being eaten by other carnivorous fish.
2. Sleep in the sand: For some demersal fish, they have better camouflage when sleeping, allowing themselves to drill into the sand at the bottom of the water to avoid all kinds of dangerous things.
3. Sleeping in bubbles: Some fish can secrete special gelatinous substances to form a layer of bubbles on the surface of the body, which can wrap themselves up, and the texture is very hard, so that they can rest safely.
4. Sleeping while swimming: There are some special fish in the ocean. Their metabolism is very vigorous, so they can't stop at all. They have to swim all the time. Even when they sleep, they will swim while sleeping, such as tuna, shark and so on.
