Should I Turn My Fish Tank Light Off at Night?

To keep the aquarium light on all night or not to keep the aquarium light on all night—that is the question: Whether 'tis nobler to give your fish a bit of darkness in the evenings, or risk stressing them out with a perpetually lit tank? Seriously, though, If there's one you don't want to do, it's stress out your fish. And fish do stress easily, especially if their environment has been altered drastically.

Aquarium lighting serves various purposes from spotting tank problems to regulating the eating and sleeping of your fish, but periods of darkness are necessary in order to mimic your pet's natural environment. Just imagine your fish swimming in the ocean as the sun sets and the waters gradually darken. For a number of hours per day, darkness rules and fish sleep. So, in artificial lighting, how much darkness should aquarium fish have each day?

Let There Be Light (and dark!)

Light and dark requirements for fish species may differ slightly so it's best to check with your fish's individual requirements. Finding the right combination is necessary so you do not stress your pet. The standard requirement for aquarium lighting for fish is usually 12 hours of light each day. Improper lighting can make your fish lethargic or ill and fish such as goldfish will lose their color or their appetite when stress rears its ugly scales!

Other Problems From Light

Excessive light can cause algae overgrowth that will make your tank look dirty and dingy. Your natural plants (which require at least 12 hours daily of light) will suffer too if algae overgrowth becomes a problem due to a tank lit for 24 hours a day. Reducing the amount of time the light remains on should reduce the problem.

Stressing your fish, of course, is a major concern. When your fish become stressed, so do you, and what was once supposed to be a calming aquarium now becomes a nerve wracking mess and there goes your calming tank environment! When any animal stresses bad things begin happening. In the case of fish, the 'bad thing' may be once-calm fish fighting with each other!

Automatic Dimmers

Some people use automatic aquarium dimmers to recreate the effect of sunrise and sunset. These dimmers calm your fish by bringing up or lowering the light over a period of a quarter hour or so after which you can set the lights to your desired brightness. These light timers are probably the most effective and easiest manner of replicating your fish's night and day cycle. If you don't want to go this route, you can use alarms to remind you each day as to when to turn the lights on or off. Also, a cheap appliance timer may do the trick if your bulbs don't eat up too much power. Use it to turn your lights on and off every day at the same time and set it up for an 8 hour cycle.

Heat Lighting

Warming your aquarium with a heat light may not be warm enough, especially for tropical fish. An aquarium heater may need to be used instead or you can buy ceramic bulbs that produce only heat and no light because some heat lights may be too bright.

By Tom Matteo


About the Author
Tom Matteo has been a freelance writer since 1992. He specializes in hardware and software reviews for computers and gaming systems, and occasionally writes about such topics as animal behavior and care. Tom resides in Bethlehem, PA with his wife Tina and his beloved cockapoo, Angel.