Do fish sleep?

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Just one of those random discussions but now I'm kind of curious. Do fish actually have an unconcious state similar to what we'ld call deep sleep? So that they wouldn't react to most stimuli, excepting a sudden pulse in the water?
 

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This has also been one of the questions I've asked when I was younger. A quick google search gave me some information, although I do not know how legitimate and accurate this information is.

It seems that fish can "sleep" (more like rest) in an energy-saving state. Some fishes that live near coral reefs actually hide in the spaces between the coral when they "sleep" to avoid predation. Other fish "sleep" under logs or large rocks to avoid predation.

Just an aside, what is the definition of sleep? Some people sleep with their eyes open, most with their eyes closed, but they all sleep the same.
 
  • #3
I think he's talking about 'sleeping' in the way mammals do. Then again, I understand why he'd ask such a question because of the conflict with their aquatic environment.
 
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Phobos
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Fish do sleep, but certainly differently than we do. I've observed (and read about) the semi-conscious state of their sleep. They still swim (like hovering in place) in a safe location and are generally oblivious to things, but still aware enough to snap back to attention if something threatening advances on them. I'd say it's a safe bet that different species of fish have different variations on sleeping.
 
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How well can fish unconsciously hold their position when ‘sleeping’?
 
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  • #6
nautica
Position would be held by their boyancy. This would not need to be maintained through a conscious effort. Although, they can change this to change depth.

Nautica
 
  • #7
Chronos
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Of course fish can't sleep, they would drown...
 
  • #8
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Something underwater (maybe "fish" is too broad of a category) is said to have a brain that sleeps one-half at a time. Can't remember where I read that, though.
 
  • #9
in response to kalladin the term sleep is considered when all senses have been reduced by 80% and so energy is saved and is used for other things like growing. we can solve 30% of problems or questions during sleep because our brains turn off our senses it have less information to take in and we in turn become less aware of our surroundings. people day dreaming are people normally who don't get enough sleep and so their brains, at a time when they are not so active like in a lecture or boring class, reduce reactions from senses and so uses that energy conserved to provide the body with the much needed growth and energy and look to other people as sensless and away in another world as it were, that is where the term day dreaming comes from.

if have anymore questions just ask

day without sunshine ..........is like..........well...................night!!!
 
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Phobos
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First two hits from Google on "fish + sleep"...

http://www.newton.dep.anl.gov/askasci/bio99/bio99047.htm
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. Many fish, like Bass and perch, rest on or under logs at night. Coral reef fish active in the day, hide and rest in crevices and cracks in the reef to avoid being eaten at night. The resting behavior of fish is very different from their behavior the rest of the day. Many minnows, for example, which are very active in schools during the day, scatter and remain motionless in shallow water at night. Many fish "rest" or "sleep" during the day and are active at night instead, but almost all fish sleep. There are some animals that never stop swimming, like many species of
shark, however, they HAVE to keep moving to push water through their mouths in order to breathe, and they may still sleep while moving,
we just don't know yet.
http://www.nefsc.noaa.gov/faq/fishfaq1.html
...Also, while some deep ocean fish never stop moving a great many fishes live nearly motionless lives and many do so on a regular diurnal/noctural cycle, some active by day others by night.. So we can't generalize and say that all fish sleep like we do. But most fish do rest. Usually they just blank their minds and do what we might call daydreaming. Some float in place, some wedge themselves into a spot in the mud or the coral, some even build themselves a nest. They will still be alert for danger, but they will also be "sleeping."

Chronos said:
Of course fish can't sleep, they would drown...
:confused: joking? or are you thinking of sharks, as mentioned above?
 
  • #11
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Phobos said:
:confused: joking? or are you thinking of sharks, as mentioned above?
Just kidding. Certain fish appear to spend most of their time in a state best described as sleep. I used to have an aquarium with this fish that stuck to the side of the tank. The guy at the fish shop sold it to me saying it would keep the glass clear of algae. I once calculated how long it to make one pass across the entire tank: about 11 years. It actually moved about four times a week. The rest of the time it spent pasted in place like a stunned slug. One time I saw it swimming around in the tank. My first thought was that it had died. That thing either slept 99% of the time or was the most easily amused creature I have ever encountered.
 
  • #12
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you forgot to calculate how fast the algea and other things would grow on the tank...plus, those suckers (almost literal name) can grow pretty big, depending on how big the tank is.
 
  • #13
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I thought fish turn off half of their brain and keep on going with half power. Like keeping on swimming, but not consciously.
 
  • #14
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Chronos said:
Just kidding. Certain fish appear to spend most of their time in a state best described as sleep. I used to have an aquarium with this fish that stuck to the side of the tank. The guy at the fish shop sold it to me saying it would keep the glass clear of algae. I once calculated how long it to make one pass across the entire tank: about 11 years. It actually moved about four times a week. The rest of the time it spent pasted in place like a stunned slug. One time I saw it swimming around in the tank. My first thought was that it had died. That thing either slept 99% of the time or was the most easily amused creature I have ever encountered.
:rofl: Maybe there's a business opportunity in breeding fish with brush-like fins to keep tanks clear of algae.

FWIW, when I had aquariums, my sleeping fish would simply hover in a quiet corner. Perhaps I should have turned up the filter pump rate to push them around a bit more. :smile:
 
  • #15
i have an aquarium of gold fish and they move around quite alot even though the tank is small, i had to put a lid on the top of it to stop them jumping out. maybe they saw finding nemo?
 
  • #16
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Well, i have observe that fishes do sleep - or at least, the species of the fish that I keep. At night, my fishes would remain motionless at a single spot with their eyes turned pale (Sometimes, they even lie down on their side when their sleep! ).
 
  • #17
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I would say yes fish do sleep, but in a different way then we mammals. I have had fish since I was a young boy and now I can say that I have seen fish sleeping. Currently I have two small comet goldfish in a ten gallon tank. I remember getting up in the dark of night because I could not sleep or I needed a drink or bathroom ect. I remember looking at my two fish to feed them it was winter and I had been sleeping and the lights had been off for no less then 4 hours and there had been darkness out side for at least five hours. I remember having not feed the fish that day so I thought to feed them and when I turned on a dim light I saw one fish that looked like it might be dead or dieing. This fish was on the bottom of the tank in a spot where the current of the tank pump my have left a fish if it was dead, a spot in the tank of low current. I put some food in the tank and there was no responce from the fish at first. I saw the fish moving just enough to keep from drifting around in the tank. The goldfish looked like it was on auto pilot and sleeping. The goldfish did not even move when I put the food inside the fish tank, and the gold fish was nearly moving. Any one who is a big fan of goldfish will know that any goldfish that is not sick would never wait long to get food inless it had already eaten its fill. My goldfish had not been feed all day so they would be very hungry, as goldfish are always hungry and live to eat. After a minute and after I banged on the glass of the fish tank the fish "woke up", and became aware again and started smimming and looking alive and then hunted for food as it would normaly.

So with the above said in mind I firmly believe that fish do have a form of sleep almost like deep transe where only the most basic outward actions of the fish take place, just enough outward action and responce that is done as an automatic brain responce as the fish essentially sleeps.


Any coments or responces?
 

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