Do Glofish Need Light All The Time?


Water changes, feeding, and other simple tasks require adequate light.  But in the case of GloFish, correct lighting also means being able to see their spectacular glow-in-the-dark colors.

In this article, we will discuss the kinds of light, its effects on fish, and which ones would bring out the best in our GloFish tank.

Do Aquarium Fish Need Light?

Light is essential for all life on earth, including fish.

Yes, aquarium light is needed not just so we can perform basic tasks in the tank, but also for the fish’s physiological health.  Light is also a necessity to grow beneficial bacteria and some algae in the aquarium.  Therefore, light affects the balance of life inside the fish tank.

Fish uses light to see food and capture its prey (in the case of live food).  Light also stimulates growth in fish, especially in fry. 

The amount of light the fish receives also affects their pigmentation.  Non-GloFish species have lighter colors with long exposure to bright light and light-colored substrate.

Light is basically used in an aquarium to simulate daylight in the wild.  Without daylight, the basic biorhythm of fish becomes abnormal, affecting their feeding, resting, and breeding habits.  Basically, proper lighting ensures normalcy in the life of a healthy fish.

Does GloFish Need Light?

Because GloFish are bioluminescent, it is essential for them to absorb light in order to emit it.  So they need aquarium lighting.

Your live aquarium plants need light, too.  Without it, there would be no photosynthesis taking place and your plants will soon wither and die.

In the same way, algae growth is enhanced by the intensity and amount of daylight it receives. 

Glofish Needs Light
Glofish Needs Light?

Since artificial light has replaced natural daylight in the fish tank, the control of what kind of light and when to turn it on and off is controlled by you.  Thus, you should do it responsibly knowing that all organisms in your aquarium rely on it.

Do GloFish Need Light All The Time?

There is a necessary balance in the biological rhythm of any organism which daylight and night regulates. 

GloFish need the kind of light that simulates daylight and night to keep them healthy and balanced.  This means that you should leave your light on at a certain part of the day, and then turn it off to mimic nighttime.

We’ve already discussed in our article here that GloFish “sleep”, being the diurnal creatures they are.  Even if they can’t close their eyes because they don’t have eyelids, fish slow down their activities at night.  It doesn’t matter if your fish was totally captive-bred, they would need light to simulate daylight for activity as well as darkness to simulate night for rest.

Fish need to rest, too.  In fact, too much light would be stressful to fish, even GloFish.  Remember, GloFish varieties are no different from other aquarium fish except for their glow-in-the-dark colors. 

Constant bright lights, sudden changes in light, or too intense lighting can be stressful to fish. 

And stress compromises a fish’s immune system, making it weak and prone to diseases and infections.

Another reason why you shouldn’t leave your lights on all the time is the danger of having an algae bloom.  Too much light prevents live plants from absorbing all the nutrients in the water, giving way to algae growth.  Too much algae is bad for tanks because it uses up the oxygen in the water.  And if oxygen levels are too low, your GloFish will find it hard to breathe.

How Many Hours Of Light Do GloFish Need?

Because aquarium light simulates real daylight, you should have roughly the same hours of lighting as outside.

We suggest you start with 8 to 10 hours of light per day.  Observe if green algae starts to grow rapidly.  If it does, cut the light time by an hour until you find the right balance. 

You will notice algae growth in as little as 1 to 2 days, so adjust your light time accordingly. 

To curb the growth of algae, use lots of live plants in your GloFish tank.  You may still insert the odd glowing plastic plant for décor, but live plants have more benefits to your fish than plastic ones do.

Do Different Colored Lights Affect Fish?

With so many kinds of tank lights out in the market, it’s become confusing for many hobbyists to choose the right kind of light to put in their aquarium.

Glofish Under The Lights
Glofish Under The Light

Yes, different colored lights have different effects to fish, GloFish included.  This is because each kind of light has its own color temperature.

What Is Color Temperature?

Visible light has color temperature.

Color temperature can be described as how the naked eye sees light from a bulb.   It is expressed in Kelvins.

Different kinds of light bulbs have different color temperatures ranging in 1,000 to 10,000 Kelvins.  Those with lower Kelvins—2700 to 3000K—are considered warm and used for ambient lighting.  An example of this would be the 2700K (Kelvin) bulb on your floor lamp. 

Those with higher factors—4500K and above—are considered cool lighting and is used for tasks where a clearer view is required.  An example is a 5000K daylight bulb used as a security light.

What Light Do You Use For GloFish?

The recommended type of lighting to view GloFish best is actinic lighting.

Actinic (blue) lights have high color temperatures that range from 5000 to 6500 Kelvins.

What Is Actinic Lighting For Aquarium?

You may have heard of actinic lighting for fish tanks as they are sold everywhere.

Actinic light refers to the component of sunlight that is able to penetrate water.  In a spectrometer, actinic light mostly registers in the blue spectrum.

Actinic lighting is the recommended lighting for GloFish so that their glow can be clearly seen.  The most actinic lights are blue lights.  They are the ones which show very little red emission in the color spectrum.  These are also the kind of lights that saltwater fishkeepers use in their tanks because it allows the fish to rest while enhancing coral growth.

A study on the Nile tilapia showed that compared to other colors of light, blue light is most effective in reducing stress in fish.

Can I Leave Blue Light On In Fish Tank?

We told you in our post here that blue light is best for GloFish to show off their glowing colors.

Actinic blue light is meant to mimic moonlight and can be left on all night.  However, it’s not a necessity for your GloFish’s survival and can be a waste of energy since you don’t have saltwater corals to support anyway.

We suggest turning off your blue light before you go to sleep at night.

The best way most GloFish hobbyists use their bluelight is when during the last part of the day and upon waking up in the morning.  They use it as a half-hour or hour-long transition from light to dark or dark to light so that the GloFish’s eyes can adjust to the change. 

There have been studies about fish eyes, particularly salmon eyes, which prove that it takes them about half an hour to adjust to changes in sunlight.  It might even be slower in artificial light if the change is not anticipated.

Do Blue LED Lights Cause Algae?

Since algae cannot utilize blue and violet lights to spur growth, using actinic light in an aquarium will not trigger an algae bloom.

But if you use light that has more red in the color spectrum, then algae might grow very quickly.

Are LED Or Fluorescent Lights Better?

There are also fluorescent lights in the market available for use in aquariums.

LED’s are considered better than fluorescent bulbs because LED’s emit considerably less heat than fluorescents.  LED’s also last longer as they are more energy-efficient.  They shine a brighter light using less energy compared to fluorescent bulbs.

A lot of hobbyists suggest upgrading to the longer and brighter actinic lights as they give you the best view of the GloFish’s colors.

What Color Light Can Fish Not See?

As it turns out, these actinic LED blue lights are invisible to fish. 

Is Sunlight Good For Fish?

Since you’re trying to mimic the wild, you might think that exposing the tank directly to sunlight may be a good alternative.

Sunlight warms the water in your tank, making the temperature unstable.  Sunlight is therefore not necessary if you have good white and blue LED’s in your GloFish tank.

It’s not advisable to put your tank near the window to catch sunlight to avoid fluctuations in the temperature that might stress your fish out.

Recent Posts