Do Fish Sleep?
Updated: Feb 12
The phrase "early bird gets the worm" is one that is often applied to fishing. The idea that the earlier you are able to hit the water the better chance of catching fish you have. Sunset is also another period associated with catching fish while mid-day is typically a lower fish activity period. At New Wave Fishing Academy we know that by adjusting strategies anglers can keep the bite going all day long (to learn how you can do this be sure to check out our Zero To Hero Fishing Masterclass at www.newwavefishingacademy.com/zero-to-hero ). However, this raises an interesting question, if fish are most active early in the morning and right before dark do they sleep or are they nocturnal? Fishing after dark is something more common with Walleye anglers but bass, muskie, and salmon anglers often find success doing the same thing!
This question got us thinking and we needed an answer! Scouring the internet we've compiled some interesting facts on the topic that have opened our eyes to fish behaviour we had not considered previously. So, what did we discover? Fish do "sleep" but it's not quite the same as for us.
1. Sleep Cycles
Aquarium fish have been shown to sleep for seven to twelve hours each day! Being more active during the day and inactive at night. There are some species like Walleye, Catfish, & Sharks where this is reversed but most species are just like us.
When humans get ready to sleep we make sure we are protected first. Locking the doors, shutting the blinds, and getting under the warm blankets, all help us feel safe and secure since we won't detect danger while asleep. Fish don't quite have this luxury. While fish do enter a period of rest that is equivalent to what we consider sleep it is not the same as terrestrial (land based) animals. Research in this area is ongoing however studies show that most fish enter a state of suspended animation where they will float or secure themselves in a location while reducing their activity & metabolism. Unlike terrestrial animals fish are still alert to danger while in this state.
3. Shutting Down The Brain
Unlike humans and most land based creatures fish do not have eyelids. While we can close our eyelids to help shut down the part of our brain that processes sensory information to enter sleep fish can't! In addition, fish have many more sensory organs for understanding the world around them beside their eyes. In order to enter the suspended animation fish use to rest and recover they reduce their activity, movement, and simply shut off their sensory input leaving only enough to remain alert for predators.
4. Activity Pattern
A study by Dr. Takahiro Ito and his team at Nagoya University implanted electrodes in the brains of fish, to track their brain activity patterns and see when they were sleeping and when they were awake. They found that fish do sleep, but their sleep cycle is different than ours. They typically sleep for short periods during the day (about 10 minutes) and for longer periods at night (up to two hours). So while fish may sleep for about the same length as us in cumulation it is not all at once like we do! Perhaps this is the reason why the bite can often "turn on" for a few minutes before going cold again, as the fish are moving in and out of sleep while staying in the same area. Some environmental queues (sensory inputs) that can trigger fish to come out of sleep and be on alert are baitfish activity, predators, or changing light conditions. This is also a potential reason why more reaction style baits like crankbaits, swimbaits, chatterbaits, etc can get fish to bite when it is typically a tough bite. Rather than a reaction that the food is getting away and they need to feed the commotion may be just enough to "wake" them up to feed when they are sleeping more often throughout the day.
Adequate sleep is crucial for our lifestyles. Having a better understanding of how fish perform this necessary function will almost certainly lead to more opportunities for adapting their strategies to put more fish in the boat. For more information on the topic and the data sources that were used please refer to the links below: