This Is Why Your Glofish Are Not Glowing

Glofish is a genetically modified fluorescent fish and people have been actively tank raising it for a long time. This fish comes in various colors and it possesses some unique characteristics. They are able to glow in the dark and the name Glofish comes exactly from this particular trait. Some of you may find your Glofish not glowing and in this article, we would like to talk about the major reasons behind it.

The reason behind your Glofish is not glowing is that the surrounding environment should be dark too. In order to make the best use of blue and black LED light fixtures, you need to make your room totally dark and install LED light in the hood.

Glofish is the first-ever genetically engineered fish developed in Singapore. Scientists have created this fish by putting fluorescent genes from sea anemones and jellyfish into the eggs of a tropical fish called zebra danio. 

The main purpose of creating Glofish was to discover the toxins in water and find the polluted waterways. If they glow it means that there are pollutants in the water and appropriate actions should be made to protect the local communities using these waterways. 

The initial goal was to make them fluoresce all the time but scientists have modified Glofish to fluoresce in the presence of harmful substances in the water. The first aquarium pet called Starfire Red Danio was bred in 2003 by Yorktown technologies and today there are 12 species of Glofish with different colors. They include zebra fish, barbs, tetras, and so on.

How Fluorescence And Light Make Glofish Glow?

We have noted above, that this unique attribute to glow is only visible in the dark. This is induced by a well-known biological process called bioluminescence which is what makes fireflies shine at night and scientists have been studying it for a long time.

They have created this fish by putting fluorescent protein genes from marine organisms such as sea anemones and jellyfish into the eggs of a tropical fish called zebra danio. Therefore, they got a Glofish that is glowing under a black or blue light due to these fluorescent genes and the name comes from this exact characteristic.

How To Make Your Glofish Glow More?

Glofish consists of 10% of aquarium fish and it is extremely popular among every fish enthusiast. This species is recommended especially to beginners as they are very easy to look after and don’t require a lot of effort and hard work. However, there is still some work to do in order to keep your Glofish comfortable in the tank, and here are some suggestions for it.

Is Your Glofish Glowing
Is Your Glofish Glowing
  • First of all, the fluorescent coloration of the Glofish is only visible in the dark when you use a black or blue light. Therefore, it’s a good idea to add a LED light attachment featuring blue lights. This way you will be able to witness this unique ability of Glofish.
  • Alongside the LED light you have a possibility to use a Glofish Cycle Light that can provide four unique light modes. Every mode is able to enhance the coloration of your fish and décor.
  • You have several choices when it comes to the decoration of the aquarium. If you want your Glofish to leave a pleasant impression every time you can add some artificial plants, gravel substrate, or some rockwork decoration. It’s up to your taste and style.
  • The plants in your tank need some energy to survive and we recommend establishing broad-spectrum lighting to brighten the aquarium.

Why Blue Or Black Colors Are Suitable For Glofish?

As we have mentioned above, Glofish is made of fluorescent protein genes derived from marine organisms. These fluorescent proteins need a certain type of lighting to make your fish glow.

After some time of observation and examination of different colors, scientists came to the conclusion that only black and blue light are capable of stimulating the fluorescent proteins and as a result, making the Glofish glow.

Glofish Not Glowing
Glofish Not Glowing

 If you select any other color of light, it simply will not have any effect on glowing your fish. Other colors besides black and blue don’t have any influence on fluorescent genes and they might be even damaging to your Glofish’s health.

What Kind / Type Of Light Are Available On Amazon?

We encounter different kinds of lights and lamps on Amazon for your aquarium to make Glofish glow. Our recommendation is to go for blue LED lights to experience underwater fluorescence in the best way.

There are several options to try such as Glofish Blue LED Bubbler, Glofish Cycle Light, Glofish LED Aquarium Light Bar, and so on. They all include blue LED lights that are responsible for enhancing the fluorescent color of your Glofish.

Where Should You Install LED Lights To Make Glofish Glow More?

There are various kinds of appliances to make your Glofish glow in the aquarium. You could try different positions and direction to make the colors of this fish more vibrant.

Glofish will glow brilliantly if you’d clip your LED light fixtures to the hood of the tank. This way your aquarium will become glowing and you won’t have to replace the hood every time.

My other reason to locate the LED in the hood is to create a better contrast to the dark in the room where it cancels out any UV light in the ambiance. Just like cinema, colors pop out awesome sharp and vibrant in the dark.

Does The Color Fades Away When Glofish Starts To Age?

Generally, the color fading in Glofish is not induced by aging but rather when it is experiencing some sort of stress or disease.

Probably it is not satisfied with the living conditions you provide and you need to address this issue immediately, otherwise, it may end up with fatal results.

The stress causes the endocrine system to secrete a hormone called corticosterone which is the main factor of fading the color in fish. You have to make sure that your Glofish has proper environmental conditions as well as the right diet to avoid diseases and stress.

Will The Color Transfer To Glofish Babies?

Oftentimes, people have misconceptions regarding this matter, as they think that the Glofish is injected or dyed. We would like to emphasize that Glofish is bred traditionally and their beautiful colors are transferred from generation to generation.

Glofish parents pass their unique color to their babies and this way they maintain their coloration all the time. Therefore, your aquarium will be full of delightful colors whenever a new generation appears.


In this article, we have described one of the most fascinating species of fish called Glofish. It is a genetically engineered fish featuring a unique ability to glow as the name says itself. However, people are often misunderstood regarding this attribute of Glofish and they get confused when they see their fish not glowing all the time.

We have emphasized, that Glofish does not glow in the dark unless you use a blue or black light. You can achieve this by installing a LED light attachment or Glofish Cycle Light in your aquarium. This species does not require too much effort to look after and if you know some basic rules you will keep your Glofish happy in the tank.

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