| Every creature on earth has some way of | | | | cold winter temperatures by going down to the |
| resting and so do fish. Sleep, if defined as a time | | | | water bottom. They slow their metabolic rate and |
| when rest is taking place, eyes are closed, and | | | | cease activity. With Koi fish, their digestive |
| there is no thought or moving around, is | | | | system even closes off so they do not get |
| something that happens in fish. Because most fish | | | | hungry. When temperatures warm up, they |
| do not have eyelids, they don't close their eyes | | | | emerge back into their normal living depth. |
| as such, but they do go through a period when | | | | Other types of fish become dormant during hot |
| their bodies slow down and they are not going | | | | and dry weather periods instead of cold ones. |
| anywhere. It might be in reality more of a rest | | | | Some fish sleep in the mud. Carp are one |
| than a sleep but to the fish it has the same | | | | example of this behavior, as is the African |
| effect as a night's sleep has on humans. It is also | | | | lungfish. Lungfish often cover themselves with |
| why in aquariums, lights are turned off so that | | | | mud and leave a little hole through which to |
| the fish sleep at least a portion of every day. | | | | breathe air. One of the most interesting of all |
| No one knows why fish sleep. It might be | | | | examples of fish sleeping is one of the gobes that |
| because, as in people, their bodies need to have a | | | | lives in the Ganges River. These fish are amazing! |
| recovery phase, or it might be because many fish | | | | They dig a burrow and sleep in it during the driest |
| hide away to sleep, that they use it to protect | | | | months. They breathe through their tail, which is |
| themselves from predators and regain energy at | | | | the only part of their body still touching water. |
| the same time. Scientists have studied how fish | | | | Scientists have discovered a parrotfish that lives |
| sleep or rest and they have discovered several | | | | on reefs who sleeps by squeezing himself into |
| different things. | | | | crevices. Then he excretes mucus which covers |
| Fish are known to have times when they are | | | | his entire body with a protective coating and goes |
| resting and are not aware of what is going on | | | | to sleep. Some sharks never really stop moving |
| around them. However, they do not go into the | | | | at all, as they have to be in motion to push water |
| deep REM sleep that humans do. Some fish spend | | | | through their lungs so that they can breathe. |
| time in-between being asleep and being awake. | | | | They are definitely in some kind of state of rest |
| Some kinds of fish sleep by going into a type of | | | | but there is no way to tell if it is what we would |
| hibernation. Take, for example, the Koi fish. This | | | | define as sleep. |
| fish, like many others, reacts to the coming of | | | | |