Guppies are diurnal fish, meaning they sleep at night when it's dark. Like most fish, guppies don't have eyelids, making it difficult to tell they are sleeping. Scientists know very little about the sleep cycles of fish, but believe the purpose of a night's rest is to conserve energy.
How Much Sleep Do Fish Need?
Guppies are a type of bony fish and require sleep in order to conserve energy and function. If you leave your aquarium light on 24 hours a day, guppy fish may be unable to fall asleep and will eventually die. While scientists do not know exactly how many hours of sleep a fish needs every night, most diurnal fish sleep whenever the sun sets and can therefore live off the same amount of sleep the average human gets every night. Make sure you turn your aquarium lights off every night to let your guppies get some rest.
Sleeping Patterns in Guppies
Guppies stop swimming and float when they go to sleep, causing them to sometimes appear dead. Guppies may choose to sleep by lying motionlessly on the gravel at the bottom of a tank, floating at the surface or resting near plant decorations. When they enter this state of rest, they have a lower respiratory activity rate and no detectable eye movements. Unlike mammals, they do not exhibit REM sleep and their brain waves do not change. The fish also become less sensitive to sound and tactile stimulations. Guppies kept in a freshwater tank usually stop moving when the lights are turned off.
Lights Out for Guppy Fry
If you are raising guppy fry, it's important to give them at least seven or eight hours of darkness each night. Lighting helps guppy fry grow faster, but more than 12 to 17 hours of light will deprive them of much-needed rest and relaxation they get when they fall asleep. Like adult guppies, the fry will eventually die if the aquarium light is never turned off. Guppies are most sensitive when they are babies, making it more important than ever that the young fish receive proper care.
If your guppy is floating motionlessly in your tank in broad daylight, your scaly friend is probably not sleeping -- it may indicate a more serious problem. Pregnant guppies sometimes lie on the gravel during the day, but if your fish is not pregnant, that behavior is alarming. If your guppy also isn't eating and has cloudy eyes, white spots or fuzzy patches on his scales, he could be sick. Call your local pet store or a fish expert to diagnose the problem.