Are the fishes sleep at any time?

Question

fishes or sealives

Answer 1

As fish have no visible eyelids (and closed eyes generally imply
sleep) and we see them usually by day when they
are in motion, this question is always the source of some debate.
The following account of Spotties (Notolabrus celidotus), written by David Graham, sheds some light on the nightlife
of fish in captivity. He was the biologist at the Portobello Marine Laboratory in the 1930’s and was responsible for
looking after all the fish in the Aquarium at that time. The following notes are from his book A Treasury of New
Zealand Fishes (Reed, 1953).
“… At that particular time we had no electric lights in the Aquarium and when I would walk in my rubber soled
sand-shoes no noise resulted. One night to my amazement I found all the Spotties in their tank lying on the
floor as though dead. When I switched on my electric torch, every Spotty jumped and darted madly about the
water, some even leaping about the surface in their excitement. This made me curious to know more about the
possibility that they had been sleeping or resting. So the next night when all was dark again I approached their
glass tank, taking care to make no noise. When my eyes became used to the darkness I could see each Spotty
quietly swimming to the surface and then sink, lower and lower, until each fish was resting on the concrete floor
of the tank. Soon all were stretched out on their sides. Sometimes the resting position would be changed for
a few minutes especially if the largest fish had not settled down for his sleep….After a while the Spotties
gradually quietened down, all with back fins outstretched until they seemed settled for the night….On one
occasion a large Spotty was found to be asleep standing on its tail. He had his back fins in the corner of the
tank and to all intents and purposes slept soundly. For upwards of an hour I watched him one night and he never
moved until I switched on the electric light. What happened? The Spotty almost flung himself into a horizontal
position and swam rapidly around the tank as though alarmed at being ‘caught napping’.”

Answer 2

n 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.

Answer 3

Fishes aren't sleep, not like human

Answer 4

yes a fish sleeps they dont close their eyes but u will know they r asleep when they r still at one place in the water

Answer 5

Fish does sleep.
Fish doesn't have eyelids that's why they seem to be awake all the time but they tend to sleep noticable when thay are at halt.

Answer 6

it looks like fish don't sleep because they don't have eyelids... so they can't close their eyes. also they can wake up very quickly. also, they have to make a lot of movements when they are asleep to keep themselves in a stationary position (fin movements, adjustment of the swim bladder to control bouyancy, etc.) but all of these are involuntary, just like breathing or tossing and turning in people when we sleep. so, yes.. they do sleep... but a lot of fish are nocturnal or have irregular sleep patterns.

Answer 7

fishes sleep with out closing their eyes because they dont have eye lids.they sleep with out moving

Answer 8

Yes fish sleep when the sun goes down.Even whales and dolphins sleep they turn off half of there brains.Fish just sleep

Answer 9

please see the following for a reasonable answer:

http://www.newton.dep.anl.gov/askasci/bio99/bio99047.htm

we have lots to learn about fish, and we may not be able to have same definitions for humans and fish....ie. define sleep...what really defines it? Does this mean sharks sleep, or only if fish do not move means sleep?

Answer 10

Yes they do sleep, but they don't remain stationary at one place.as they do not have eye-lids the don't close their eyes.But dolphin sleeps with its one open.so, fishes do sleep