Proroy fishermen and aquarium owners ask the question: does the fish sleep? The question arises for a reason, because no one has seen fish with their eyes closed. They just have nothing to close – fish have no eyelids. They do not rest in the same way as is customary for humans, birds and mammals.
sleep of fish – this is the rest phase, in which all functions slow down, the body becomes immobile, reactions are weakened. Some fish at depth do not respond to external stimuli (you can touch them, shine a flashlight in your eyes). Others feel the slightest danger. Many fish become almost immobile while resting. And some (tuna, sharks) are constantly in motion, lying on the water against the current. If streams of water do not pass through their gills, they can suffocate.
Features of rest of different types of fish
The specificity of fish rest depends on their species. So, astronotus lie at the bottom or hang upside down. The clown fish is placed on a barrel at the bottom of the aquarium. Other species simply hover motionless.
How do fish sleep in nature?
Cod – lying down, flounder burrows into the sand, herring – belly up, drifting in the stream of water. Most fish seek out secluded corners for sleep – among stones, rock crevices, algae and corals.
Not all fish sleep at night. Nocturnal predators (burbot, catfish) prefer daytime sleep. But after a restless night, a diurnal fish can afford a “quiet hour” during the day. Surpassed all dolphins (although these are not fish, but mammals). They hardly sleep. During rest, the hemispheres of their brains are awake alternately so that they can float to the surface and inhale the air. The rest of the time, both hemispheres work. In general, the features of fish recreation depend solely on their type.