Goldfish can’t close their eyes as they have no eyelids.
Goldfish can’t close their eyes, but they can sleep, just not in the same way that humans do. The fish’s eyes are located on the top of their head, just above their nostrils, and they can open and close them at will. They also have a set of muscles that allow them to turn their heads to look at the world around them.
When they’re not sleeping, however, they don’t have eyes at all. Instead, their pupils are filled with fluid, which allows the fish to see in complete darkness. The fish also has a special organ that allows it to detect light, called a photoreceptor.