Fish live in water and naturally sleep in it. Because these animals have no eyelids, they also sleep with their eyes open, so it may be difficult to distinguish if they don't look carefully. Usually, when a fish sleeps, it will stay in one place for a long time, and at regular intervals, its fins will shake. In addition, some fish sleep looking for places that are not easy to be found, such as aquatic plants or crevices in Stone.

1. Hiding in the dark: Fish live in water and encounter natural enemies anytime and anywhere, so they usually hide in the dark when sleeping to avoid being discovered. Most fish like to hide near Stone or aquatic plants, and use these things to cover their bodies, so as to ensure their own safety.

2. Drilling into the sand: There are some benthic fish, which are flat and not easy to hide in aquatic plants, but they can drill into the sand and bury themselves, which also has a good hiding effect, which can not only ensure quietness, but also avoid the hunting of natural enemies.

3. Secreting bubbles: In addition to finding a place to hide, there is also a way to protect yourself during sleep, that is, secreting bubbles, such as schizophrenia or Nanyang parrotfish, which can secrete special gelatinous substances and wrap themselves like a bubble, thus avoiding various threats.

4. Swim while sleeping: Some fish in the ocean must swim all the time in order to maintain their physical functions, even when sleeping, such as sharks and tuna, which swim while sleeping.