What are fishes sleep patterns like ?

Fish circadian rhythms are regulated in much the same way as ours. There is the same sensitivity to the light/dark cycle, regulated by the pineal gland, the retina and other light receptors, using the pigment melanin as the chemical signal. And there is also a hemeostatic component which, like for us, creates a need to balance periods of wakefulness with periods of sleep.

Because of the light/dark sensitivity, fish also have a 24 hour circadian rhythm. They do have an ability, though, to switch back and forth between being nocturnal or diurnal, depending on season, feeding opportunities or predation pressures.

Fish sleep isn’t characterized by the same kinds of brain wave patterns as ours, because we have very different brains (so no fish dreams), but they do have a limbic brain with the same neuronal structures that regulate our sleep. Fish sleep is a period of low arousal, so that a sleeping fish can be gently lifted to the surface before waking up.

We have two large oscars who park themselves side by side down at the bottom of the aquarium at night.I would say that is their sleep time. The lights are on timers so they get lights out and on exactly the same time every day.

I don’t think they sleep the same way humans do. Because their breathing seems to depend on their forward motion, I would say their are closer to being in a deep meditation than a REM cycle.

You should send this question to Luca Brasi