Do Betta Fish Glow Under Black Light?

One common reason why Betta fish is so popular among aquarists is its unique and vibrant color. It looks ethereal when a ball of color swims back and forth inside your transparent tank. But we know something that’s even better. It’s letting the fish glow under black light.

Betta fish naturally don’t have any glowing element in their bodies. But genetically modified bettas (by GloFish LLC) possess such protein DNA that fluorescents under black light. Besides this particular trait, GloFish bettas are similar to the natural ones.

If you are planning on getting a fairy betta, which also glows, you are at the right place. Before bringing the little buddy home, we will provide all the information you need. So, don’t go anywhere.

Key Takeaways

  • Natural betta fish don’t glow in the dark.
  • You have to modify a specific DNA to make the betta glow.
  • Genetically modified bettas glow better under black light.
  • Prolonged exposure to black light can be harmful to Glo Fish Bettas.

Will Every Betta Fish Glow In The Tank?

Nope. Unfortunately, betta or Siamese fighting fish don’t have that trait naturally. To glow in the dark, the fish must have fluorescent proteins in its body. Only then can it absorb UV light and reflect a vibrant color. It’s an amazing viewing experience.

Usually, the bettas that can “glow” under a black light are called “glo fish betta.” GloFish LLC is a company that owns the patent for modifying fish with that particular fluorescent protein.

Why Do Some Betta Fish Glow In The Dark?

As we have already said, betta fish will glow if it has been genetically modified in the lab. But that brings us to our next question. Will a GloFish betta glow in the dark? Or does it need black light especially?

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GloFish betta naturally is brighter in color. The stripes or patterns in their bodies are easily distinguishable. So, even in the dark or under blue light, their color pops out. you can see them more clearly than their other tankmates. But to really see the “glowing effect,” you must turn on a black light.

Blacklight is simply UV light. You must have seen those in pet stores. It makes the fish glow, and the colors pop out in the dark. When every other light in the room is OFF, it looks like the fish are floating in the air. If you have bought bettas to add some life to your home décor, having GloFish betta will really enhance the experience. Unlike the regular ones, you get to see them moving even when the room is dimmed.

Here’s how the mechanism works. Black lights radiate 375 to 380 nm wavelengths into the tank. This is out of our visible spectrum. But Bettas can see it just fine. Once the radiation hits the fish, some of it gets absorbed as usual. The UV light causes the genetically enhanced protein inside the skin to be fluorescent. That’s why the reflected light and color are so brighter than before.

How Different Are Glowing & Regular Betta Fish?

Apart from the fact that Glo Fish bettas have fluorescence ability, there’s no major difference. The modified fish still needs the same water parameters as before. It’s aggressive, a little shy, and possessive of its territory. That’s why even Glo Fish bettas don’t prefer sharing tanks with another male competitor.

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If you want the injected protein to stay intact, try giving the fish protein-rich food. Special cans are available in the market to satisfy “glowing” fish. But you don’t have to rely on it completely. Just find a pellet brand that offers a high percentage of protein.

Can I Turn On The Black Light 24/7?

Even though black lights make your fish glow, there’s a time limit. You are not supposed to turn the lights on all day. It should not be the primal light source in the entire room. only use it for a couple of hours during the night.

Prolonged exposure to black light can hurt their eyes and make them hyperactive. It’s just how short wavelengths affect our brain (humans, too). So, try to shift between black light and natural light.

Can Black Light Burn My Betta Fish?

Black lights don’t “burn” betta fish in the literal sense. But if you mean skin damage, then we would be hesitant to say NO. You see, black or UV light produces ultraviolet radiation. The problem is not every part of this spectrum is good for betta’s skin. UV ray ranges from 100 to 380 nm. Safe black lights only use 375 to 380 nm of wavelengths in this range. Anything shorter than this can cause major irritation in the eyes, skin damage, etc.

So, if your betta is showcasing signs of a “less bright” or faded skin color, the black light might be affecting the porting thing. You need to get rid of it ASAP.

Can Betta Fish Hear

Do Glo Fish Betta Die Early?

Many people assume Glo Fish dies early. Some even claim that genetic modification is cruel and unethical. If you are thinking lab assistants inject harmful chemicals inside the fish’s skin, you are wrong. Let’s break it down.

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First of all, it’s not illegal. The fish used for modification are infertile. So, there’s no question of interrupting their breeding process. During the breeding process, such infertile bettas are separated from the rest. So, there’s no risk of passing down a new gene to its fry and creating something dangerous.

Secondly, we have not seen any case where the GloFish betta died early just because of the fluorescent DNA. It’s similar to the protein found in Jellyfish (which also glows in the dark). The process doesn’t have any side effects at all. A betta fish without any such procedure will live up to 3 to 4 years. That remains the same for Glo Fish bettas as well.

Before You Leave!!

You know black lights have some major disadvantages as well. some betta fish react badly under harsh UV light. In that case, you might have to choose another colored light to increase the beauty of your betta-tank. And how do you find the right color? Well, take some help from our article, which enlists all the colors your betta fish will like.

Article link: What color lights do bettas like?

Muntaseer Rahman

About Author

Hello, I’m Muntaseer Rahman, the owner of I’m passionate about aquarium pets like shrimps, snails, crabs, and crayfish. I’ve created this website to share my expertise and help you provide better care for these amazing pets.


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