How many hours do fish sleep?

[BlackTip]

Most of my fishes go to sleep by the moonlight, except the larger guys (tangs, foxface, and butterfly) They always swim around. Even in the morning, when there is only ambient light, they are still swim around. Especially the butterfly. He is always swimming.

Do those guys ever sleep?

 

[Deinonych]

My foxface and tang usually retire before the actinics go off, although they are pretty active almost right up until that point. They are up before the lights come on, but there is ambient light in the room well before that time. I estimate they get a good 9 hours of rest each day.

 

[Kremis]

As soon as lights go off, all my wrasses instantly go to their sleeping spots. My tangs take a half an hour to "settle in." My pyramids hover around in a "half sleep" for another few hours. Eventually they will settle down in a dead zone in the back of the tank and just hover there. They will be up before the morning lights turn on. All other fish only come out when there is light. I thought my pyramids didn't sleep, bought I caught then sleeping one night when I stayed up till 12 lol a

 

[TauntingBeef]

My firefish is a late riser gets up about 10 mins after lights on consecutively

 

[ThRoewer]

Most fish sleep as long as it is dark. In the tropics that's roughly half a day.
But as long as there is enough light for them to see some will continue to be our and hunt for food.
If your fish don't go to sleep then your moonlight or ambient light may be too strong.

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