What Color Light Do Betta Fish Like? – Warm Or Cool?

blue white gorgeous betta fish

Planning to light up your betta-tank? It’s an excellent step, considering how important a day & night cycle is for the fish. But you might get confused by all the colors available. After all, do bettas really care about any specific color? If yes, what’s that?

Blue lights work well for both day and night time. It creates a moonlight ambient without blurring the vision. On the other hand, red and yellow colors help the fish relax and rest. You can also try purple light if you want the fish to be more active.

Some people say colors don’t matter for an aquarium light. And the others insist that each color has a certain behavioral impact on the betta. We won’t say which one is true just yet. You have to read the article to find out.

Key Takeaways

  • Bettas can see and detect colors.
  • Betta fish’s visual spectrum starts from 10nm.
  • Green light should be avoided if you have a planted betta-tank.
  • Colors like red or orange reduce the betta’s anxiety.
  • Bright white (above 6500K) should be avoided as it can be too harsh.
  • Bluish color tones keep the betta more active throughout the day.

Do Betta Fish Care About Light Color?

There’s a common misconception that bettas don’t see color. Their eyes see everything in black & white. Well, a recent study shows different results. In fact, Bettas do see colors. Maybe their sense to distinguish each color is not as sharp as a human’s. Their iris is slow and takes a lot of time to adjust to various light settings. But they have enough photoreceptors to tell the color of different objects near them.

But they don’t see color when it’s dark. Their eyesight is not that keen. However, even in vague lighting, they can figure out an object’s shape. So, if you were thinking your betta wouldn’t care what color light you pick, you are wrong. They might not care enough, like a change in water parameters. But you can notice their reaction to different light settings.

Instead of asking which color they like, you should be more concerned with the colors they hate. Colors don’t benefit the betta in any major way. some colors might help them see better or feel comfier. But that’s about it. You should be more concerned with too harsh lighting on a betta’s eyes.

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Do Bettas See Every Color In The Visible Spectrum?

Bettas actually have more cons in their eyes than humans. Reportedly, they can detect 250+ colors without any trouble. Thanks to those extra con cells, Bettas can see colors in sharp detail when the object is nearby. By near, we mean only a few feet away. Unfortunately, bettas can’t identify color if the object is far away. So to speak, as long as the object is near, bettas can see every color in the visible spectrum.

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Not just the visible spectrum, betta fish can see light that is even invisible to humans. We are talking about ultraviolet light. Such lights are available in the market as “black lights.” These lights radiate UV-A rays that humans can’t see. But a betta fish can see everything clearly under such lighting and carry out the daily tasks.

The range of UV-A wavelength is 315 nm to 380 nm. Most black lights radiate UV rays of 375 nm wavelength. It’s the safest option out there. Choosing black lights with shorter wavelengths (like 253 nm) can hurt the betta’s eyes. Apart from the distance, there should also be adequate light in the tank. Just like humans, bettas don’t see anything in the dark. They have to rely on their other senses, like smelling or touching completely.

What Color Light Should I Install In A Bett-Tank?

You will get a specific reaction from the betta depending on which color light you choose. To make the right decision, you have to know how each color influences the fish to behave a certain way.

A little short on time? Check out the table below and get a brief answer.

620 to 750 nm400 to 480 THzRedLowest stress level
590 to 620 nm480 to 510 THzOrangeMore relaxed
570 to 590 nm510 to 530 THzYellowResembles sunlight
490 to 570 nm530 to 600 THzGreenAlright, but not good for plants
450 to 490 nm600 to 620 THzBlueStays more active
380 to 450 nm620 to 680 THzVioletSees better

 Now that you briefly know which color does what, let’s elaborate. Shall we?

1. Ultra-Violet: 100 To 380 Nm

We have said earlier how bettas can see wavelengths below 380nm. From 100-380 nm falls into the ultraviolet spectrum. But bettas can go even below. they can see as small as 10nm wavelength. It’s astonishing. That’s why you will see people install UV light on their betta tanks. Even though humans can’t see anything, bettas surely do.

One interesting fact about UV light is its comparatively shorter wavelengths. It’s even smaller than violet wavelengths (that’s why it’s called ultraviolet). And we know shorter wavelengths can penetrate objects better. It’s true for eyes as well. Hence, a UV light has the capacity to penetrate betta’s retina better than other lights.

It’s reported that bettas enjoy the clearest vision under UV light or black light. But there is a big issue with UV light. It’s the harmful side effects. It’s extremely important to check which kind of UV ray the light emits. Since you can’t see UV radiation at all, it’s even harder to detect whether it’s too much. All you can do is rely on the descriptions written on the light’s package.

You see, anything shorter than 375 nm has the ability to damage your betta’s skin and hurt their eyes. That’s why even though bettas see clearly, they sometimes behave weirdly under UV light. It’s because the radiation is too sharp for their eyes. So, do your betta a favor and try to avoid black lights without doing proper research on the effects of UV radiation.

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2. Violet: 380 To 450 Nm

The betta is in a safe zone once the light goes past the 380 nm wavelength. The light you see from 380 to 450 nm is violet. It has the highest frequency and shortest wavelength on the visible spectrum. It’s a good thing. It means the light will be able to reach the betta’s eye without getting distorted. The thing with shorter wavelengths is that they stay intact until hitting a certain object.

So, the violet light won’t be absorbed by the water. As for your betta’s liking, they can see clearly under violet light. It stimulates their brain to be hyperactive. You might see them swimming more than usual when the light is turned ON. It is not a bad thing to be active or energetic.

Another plus point of violet light is that everything pops out. If the betta fish or its tank doesn’t have many attractive features, wait until you see them under violet rays. Everything looks super fancy. You don’t have to spend money on extra decoration. Just the light is enough to grab anyone’s attention to the tank.

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3. Blue: 450 To 490 Nm

After violet, blue is the coolest tone in the RGB spectrum. It ranges from 450 nm to 490 nm. Betta’s see blue clearly. The color has an ability to stimulate bettas to become more “awake.” You will find the fish moving more than usual. It’s a good thing if your betta never leaves its nest. Blue light can stimulate the fish to shake off all the lethargic energy.

Another benefit of blue light is that it doesn’t interfere with the sleeping pattern. Some lights are just too harsh. So, the fish has to wait till the lights are out. only then can the poor thing rest. But blue light has the opposite effect. It creates an ambient close to what moonlight does inside water. the vision is clear yet not too extreme. If the fish gets tired, they can just fall asleep without any problem.

It’s a good thing if your betta takes naps sporadically. That means the nap time is scattered throughout the day. So, it is hard for the owner to keep track of it and control the lights. Instead, you can just use a blue light. It’s soothing for both day and night time.

4. Green: 490 To 570 Nm

Green is a very unusual color for an aquarium light. People don’t use it because of the plants inside their tanks. Most betta tanks flaunt lush green decorations. To make sure the plants grow at a steady rate, you have to provide light. But not just any color light.

Plant leaves don’t absorb green color. When white light hits the plant, it absorbs every color except green. Green is the reflected color. That’s why we see plant leaves to be green. Here, it becomes more interesting. Once you use green light for an aquarium, it doesn’t get absorbed into the plants. Some portion of the light does, but most of it is reflected in the water.

That’s why plants don’t grow as much under green lighting. Hence, we won’t suggest you use green lights for a planted betta-tank. But what if the tank doesn’t have any plants? In that case, green light has almost the same effect as any other cool-toned light. The betta is comfortable doing its daily swimming and eating.

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5. Yellow/ Orange: 570 Nm To 620 Nm

We combined yellow and orange light, considering it gives the same effect underwater. There’s not much difference. Any wavelength from 570 to 620 nm will give a warm hue underwater. It resembles the sunrise or sunset. It’s like living in murky water in a paddy field for your betta. The color is good for imitating sunlight. But we don’t suggest you also turn them on at night. You wouldn’t want the fish to think the sun is still up.

Also, yellow light doesn’t benefit plant growth much. It’s better than green light, but it doesn’t encourage photosynthesis. So, if your aquarium is full of plants, you better stay away from such lighting.

6. Red: 620 To 750 Nm

Last but not least, we have red. It has the longest wavelengths in the whole visible spectrum. The good side is that red light is never too harsh. If anything, it helps the fish feel more relaxed. We highly recommend a red light if your betta is shy and doesn’t leave its nest. Red light makes the impression that the fish is not always being watched. It is even effective for treating hyper-anxiety.

Such symptoms are common if the betta doesn’t like its new tank. You can use red light during the night time to help it rest or sleep better. Reports suggest that Bettas showcase a healthy growth rate along with increased brightness of their body colors under red lights. So, that’s something you should really consider.

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Can I Use Bright White Light In A Betta Tank?

Most people stick with traditional white LEDs for their betta-tank. it’s simple and easily available. But it doesn’t make the tank look fancy. If you don’t mind that, you should definitely go ahead and buy a white light. However, not every white light gives you the same effect. Some white lights look cooler (give a bluish tone), while the others are similar to halogen lights. So, what do you choose?

Color TemperatureRemark
1000kVery dimmed (gives red hue)
2700kOrangish white
3100kWarm white
4500kNeutral white
6500kbright like daylight

 As you can see, a lower kelvin rating means the light is warmer. So, if your white light is 3100k or below that, the light will give a yellowish tone. If you go to the opposite end of the table, you see 6500k. It is the color temperature of daylight. Your aquatic plants will love this light, especially if you own high-light-demanding ones.

Next is 4500K, which is more like the white light we have in our residences. The problem with this tone is it looks very artificial. In nature, the bettas never encounter such white light. The sunlight gets absorbed in water and gets quite dimmed before entering the betta’s retina. So, having a 4500k light hanging on top of the aquarium can be shocking. The bettas might feel overstimulated and want to hide immediately.

After that, we have 3100k, which translates to warm white. It resembles the sunlight accurately. And so does the other two tones. The light will be dim and not in your face. It’s relaxing, to be honest. But your betta might miss the bright daylight. Now it’s up to you; which color temperature you would allow in the tank.

Before You Leave!!

Adding a color light brings so much life to the aquarium. But do you know what is even more fun? It’s installing a black light on the tank, and watch your betta glow in the dark. You can read our next article on “Do bettas glow under black light” to understand the concept better. We promise it’s fun.

Article link: Do bettas glow under black light?

Muntaseer Rahman

About Author

Hello, I’m Muntaseer Rahman, the owner of AcuarioPets.com. 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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