Do fishes sleep?

Question

i just wanna know

Answer 1

Yes

Answer 2

This is a complex question with no simple answer. Deciding if a fish is asleep depends on many factors, one of which is the definition of sleep.

In humans, the transition to sleep (or even closing the eyes) involves specified changes in the pattern of brain waves in the area of the brain called the neocortex. Fishes don't have the same degree of neocortical development as mammals and thus don't display these brain-wave patterns associated with sleep (view figure of a shark brain). So, as far as brain-wave patterns go, fishes don't sleep.

If, however, you define sleep as a combination of a reduced metabolic rate, slowed physical activity, lowered response to stimuli and the assumption of a resting posture, then many fishes do sleep. Perhaps the best-known 'sleepers' are the parrotfishes (family Scaridae). Many parrotfishes find a suitable spot on the seafloor and secrete a mucus envelope in which they spend the night.

Such fishes normally swim away from a diver by day, but can easily be approached and even gently handled at night. Many fishes, however, seem not to sleep. Pelagic (glossary) species such as tunas and some sharks never stop swimming. One theory suggests that during sleep, sensory information (predominantly visual) gathered during the day is processed to form memories. Fishes that swim constantly in blue oceanic waters receive little 'unusual' visual input and require less 'memory-processing time' and thus need no sleep. This is supported by studies on several species of blind fishes that live in caves. These sightless fishes do not sleep.

Having said all that, though, I did enjoy the simple answer of a young neighbour who told me with confidence that fish can't sleep because they don't have eyelids.

Answer 3

This is a complex question with no simple answer. Deciding if a fish is asleep depends on many factors, one of which is the definition of sleep.

In humans, the transition to sleep (or even closing the eyes) involves specified changes in the pattern of brain waves in the area of the brain called the neocortex. Fishes don't have the same degree of neocortical development as mammals and thus don't display these brain-wave patterns associated with sleep (view figure of a shark brain). So, as far as brain-wave patterns go, fishes don't sleep.

If, however, you define sleep as a combination of a reduced metabolic rate, slowed physical activity, lowered response to stimuli and the assumption of a resting posture, then many fishes do sleep. Perhaps the best-known 'sleepers' are the parrotfishes (family Scaridae). Many parrotfishes find a suitable spot on the seafloor and secrete a mucus envelope in which they spend the night.

Such fishes normally swim away from a diver by day, but can easily be approached and even gently handled at night. Many fishes, however, seem not to sleep. Pelagic (glossary) species such as tunas and some sharks never stop swimming. One theory suggests that during sleep, sensory information (predominantly visual) gathered during the day is processed to form memories. Fishes that swim constantly in blue oceanic waters receive little 'unusual' visual input and require less 'memory-processing time' and thus need no sleep. This is supported by studies on several species of blind fishes that live in caves. These sightless fishes do not sleep.

Having said all that, though, I did enjoy the simple answer of a young neighbour who told me with confidence that fish can't sleep because they don't have eyelids.

Answer 4

I think you mean do fish sleep?
yes they do...Most all fish spend time in an energy-saving state that can be called
"rest", and we might even call their behavior "sleep", though it is probably
different than "sleep" in most land
animals.

hope that helps. =]

***Just becuase they don't have eyelids, DOESN'T mean they can't sleep or rest! People are trained to sleep with their eyes open too, so yes it is possible!***

Answer 5

I'm pretty sure not. My goldfish sometimes go to the bottom of its tank and stays there for a while, and then swims around again. I guess it's a fish's way of relaxing. =P

Answer 6

i think so...or at least rest. when i had a gold fish he would sink to the bottom and stay there when the lights were turned off and start moving again when the light were turned on.

Answer 7

my fish just sinks to the bottom of the tank at night

Answer 8

Yes and it's 'fish' not fishes

Answer 9

yea I think they do they would have too but. I think they do sleep with there eyes open..everyone has to rest at some point and time

Answer 10

Yes!