To be able you sleeping with your eyes open? No, you need to lower the eyelids to sleep. Because of this fish do not sleep as we do. The lids they do not, they simply have nothing to drop on the eyes. But when the darkness of the fish to sleep. Some even manage to lay on my side. The eyes of fish and humans alike. But there are differences, eaterie due to the fact that the person is in the air, and the fish in the water. As in humans, in fish there is the iris that surrounds the pupil. Most fish, the pupil changes its size.
Many fish eyes are located on both sides of the head. Each eye is able to see the picture with only one hand. Because of this the fish a wide field of view on both sides, at times more than a human. They can see in front of him, behind him, above and below. And just before the nose of the fish can be focusing the two eyes on the same object.
Experiments prove that some fish see colors. They can distinguish between red and green, and even blue and yellow. But researched a lot of breeds of fish. Because of this, it cannot be concluded that all fish distinguish color. Between the fish there are huge differences.