Yes! However, it is not exactly the same as how humans sleep. There are some obvious differences; fish don’t lie down, tuck themselves into bed and close their eye lids! In fact, only shark species have eyelids and they use them to protect their eyes when they have close encounters with other fish. Others differences are less easy to spot, like the fact that fish never go into REM sleep and some shark species have to keep swimming while they sleep, as they need constant water flow over  their gills to breathe. But the general idea is the same as in humans, sleep is a period when activity and metabolism slow way down as a way to conserve energy and restore the body. So how do you spot a sleeping fish? Depends on the fish species, but it just looks like the fish is daydreaming. Some fish sleep in coral, others sleep close to the bottom and some nestle into sand. Depends on each fish and each habitat!