Ask An Angler: Do Fish Sleep?

There are many slow fishing days on the water when anglers begin to ask themselves all sorts of questions. “Why aren’t they biting? Where are all the fish? Are they sleeping or something?” Wait a second, do fish sleep?

The answer is yes, fish do sleep. Fish need rest just like humans and other animals, but the way in which fish catch their zzz’s is quite different from how most animals sleep.

The sleep patterns of fish vary depending on the species, but all fish go into similar states of extreme inactivity to restore their bodies and regain energy. Some fish lie near or on the bottom when sleeping while other fish must constantly swim to push water over their gills to breathe. Just imagine if humans had to constantly move while they slept, we would all need treadmills for beds.

Do Fish Sleep Like Humans?

While fish are asleep they are not completely unconscious. Most fish maintain a high level of awareness to protect themselves if a predator comes by while they are napping. This phenomenon is often observed by scuba divers. Divers will get close to fish that appear to be sleeping and then the fish will sense the diver and dart away.

Do fish sleep with their eyes closed? Well, fish are actually incapable of closing their eyes. All fish, except for sharks, don’t even have eyelids. It sounds odd at first, but fish don’t need eyelids because the water constantly keeps their eyes moist. Humans and other animals, however, need eyelids so our eyes don’t dry out. Rumor has it here at MTB that The Other KVD, Karl Von Dibble, was born like a fish without eyelids. I can neither confirm nor deny this rumor.

When Do Fish Sleep?

The time of day that fish sleep also depends on the species. Many fish, like bass, tend to be more active during the day and sleep some during the night. Smallmouth bass especially follow this sleep pattern. Smallmouth are mainly sight feeders and rely heavily on sunlight to see and attack their forage. Other fish, like walleye, sleep more during the day and are more active during the night.

Do fish sleep patterns change throughout the year? All species of fish go through various cycles throughout the year such as spawning and migration. During these periods, fish sleep patterns get completely out of whack. Spawning and migration cycles affect fish sleep patterns in a way similar to how final exam week keeps college students up all night studying. After these periods are over, fish get back into a regular sleep cycle just like college students relax after surviving final exams.

Do Fish Sleep More In The Winter?

No matter where you are in the world, winter has an effect on fish behavior in that region. This effect is especially evident in northern bodies of water. Most lakes in the northern United States and Canada freeze over in the winter. It becomes difficult for warm-water species, like bass, to remain active when lakes freeze and water temperatures plummet. To cope with the cold, bass and other warm-water species become extremely sedentary and sleep for much of the winter.

The next time you find yourself tired after a long day of fishing, just remember that all those fish you caught are probably feeling the same way. Both anglers and the fish they are pursuing, need their sleep.