Have you ever seen a fish sleep?
Although fish have periods when they are relatively inactive, they don’t sleep.
Most fish do not sleep like humans where they are in a state of unconsciousness in which they are completely unaware of the world around them.
There are exceptions to this rule, however.
Some species of fish in and around coral reefs will occasionally lean against coral and take a snooze.
Fish can’t close their eyes when they sleep, because they don’t have eyelids.