Do fish sleep?

Yes, I would say that fish do sleep. Some fish actually lie on the bottom at night. Some of them even produce a gooey covering as a protection against other fish who might be looking for an easy meal. In the dark many fish have a lower rate of metabolism (their body machinery slows down), and that is much like sleep.

But there is one thing you do in your sleep that fish do not do. You close your eyes. Fish can’t do that. They don’t have any eyelids.