Do fish sleep?

[jay733]

Anyone know the answer to this? :read:

 

[beatle]

Re: topic - Yes.
Re: body - Yes.

 

[jay733]

How is it they sleep when everytime I see them they are moving their fins. Isn't sleeping when your body is completely at rest? If that was the case they would be floating up on the water, no?

 

[Snowgrrl83]

My fish definately sleep. My cichlids, angelfish, gouramis are totally out of it in the morning if I wake up earlier than usual. They sleep with their eyes open obviously and don't really notice where they are swimming or just hover that the same spot. If I wake up earlier than usual and feed them right as I turn on the light, most of them are sleeping and won't even notice I've fed them.

My puffer fish sleeps too. He sleeps under the bogwood at night and comes out during the day.

 

[beatle]

Sometimes I'll find my fish sleeping when I walk in the room, especially at night. I've found my betta likes to sleep in my java fern almost completely motionless. When I get close to the tank, he wakes up and starts swimming around again.

My cichlids will also remain motionless in their caves when it's late and the light has been turned out for a while. Move too close to the tank and they'll wake up and want food.

 

[momar]

Not all fish sleep, I think. Sharks and rays have to keep moving to keep breathing, so I would imagine they can't sleep. Maybe like dolphins and whales they only ever use half their brain at a time while the other half rests.

 

[jwddboy]

I believe all sleep but leave their natural reflexes in control of their body.

 

[twig]

I wouldn't imagine it any different that us continuing to breathe and move in our sleep.

 

[momar]

I suppose, but don't sharks have to keep swimming? I would imagine that swimming whilst asleep wouldn't be too good for them.

 

[rosita]

I believe all sleep but leave their natural reflexes in control of their body.

Most critters that can be or were prey have sleep phases. They need to be on the alert for danger, so they'll have "hover" cycles (my horses will sleep standing up, appearing completely relaxed, but if there's a huge noise, they bolt immediately; my tetra sort of hover in a group, barely moving). Mammals that sleep in small, protected places like dugouts or caves (wolves, badgers, foxes, gophers, praire dogs, cats,etc.) sack right out--often in a protective pile. Sometimes there will be a lookout, and the pod, school, herd, etc., can get a little deeper, more relaxed, or longer shuteye. Fish seem to have an automatic pilot for hover-sleep, but I've seen my gourami sleep on the tank floor, rising up in the morning. One morning I thought my black ghost knife was dead--he was lying on his side in his cave. Sleeping!!! Read up and found they're notorious for this. I'm sure other folks here have other experiences/opinions, but this is what I've observed.