Is Blue Light Good For Fish? How Can I Use It Effectively?

Is blue light good for fish

Lighting is an important aspect of any fish. So, is blue light good for fish? What does blue light in fish tank do? Please join Aquatic 247 in researching and improving your knowledge through this blog.

What is blue light?

Blue light is a component of the visible light spectrum, which the human eye can see. It vibrates in the 380 to 500-nanometer range and has the shortest wavelength and the most energy.

Sunlight is the largest source of blue light. Other sources of artificial blue light are computer screens, phones, fluorescent lights,…

Plants need blue light to survive because it provides a lot of energy for photosynthesis. Besides, blue light can give the feeling of being at the bottom of the pool.

Do fish like blue light? Continue reading the article to get the answer.

Is blue light good for fish?

Is blue light good for fish? The answer is yes if we know how to use it properly and in moderation. The best reason to use blue light is to recreate a natural environment for fish.

You need to limit blue light use to just a few hours or use low brightness during the day and turn it off at night. Normally, fish need complete darkness every night (about 8 – 12 hours). From there, we can adjust the fish’s biological rhythm.

Below is a chart showing the number of hours of light, depending on your aquarium.

  • Aquarium: 10 hours
  • Tropical fish and plants: 12 hours
  • Cold water fish and plants: 8 hours
  • No plants: < 4 hours
Is blue light good for fish
Is blue light good for fish

What does blue light in fish tank do?

Blue lights in aquariums create many environmental benefits. Below are the details that you can refer to.

Fish feel comfortable

Blue light helps reduce stress and comfort and gives them the presence of a natural environment. Besides, blue light combined with other factors can also affect their growth rate, metabolism and reproductive cycle.

Brings a beautiful atmosphere

Aquarium with blue light helps aquarists use it to perceive the aesthetically pleasing aquarium atmosphere and highlight the colors of some aquatic plants. From there, it provides the most beautiful vision than any other color.

Algae growth in blue lights

We all know that algae are autotrophs (meaning they create their food), hence they are completely dependent on light. The intensity of the light determines how quickly it develops. The rest of the required nutrients can be absorbed from the fish tank water.

Does the aquarium need blue light at night? 

The answer depends on the species of fish you are raising. Blue light becomes important when you intend to grow aquatic plants in the aquarium. However, if you provide too much blue light, it will cause problems such as excessive algae growth.

Therefore, if you want to use blue light at night as a decoration, you should choose fish species that adapt well to blue light environments.

Below are some species that you can refer to:

  • Octopus
  • Snappers
  • Squirrelfish
  • Cardinalfish
  • Moray eels


We’ve compiled some common questions about blue light. You should read to understand more information.

Is blue light bad for fish eyesight?

Some studies suggest that blue light damages the retinas of goldfish and zebrafish. However, this is rare, and there is little evidence that blue light is harmful to your fish.

Does an aquarium with blue light affect the reproductive cycle of fish?

Blue light is unlikely to affect the reproductive rate or development of juvenile fish. However, improper use of fish blue light can inhibit reproductive hormones and affect the reproductive process.

Besides, there is a study on using blue light properly to help guppies and rotan fish develop better from hatching to adulthood.

Does a fish-only tank need blue light?

Fish have no biological need for light. Therefore, if there are no living plants in the tank, you should use very little blue light. (about 2–4 hours per day).

Why do plants need blue light?

Most plants need blue light to make chlorophyll, which is the green pigment present in plant cells. Chlorophyll is essential to photosynthesis; without it, plants would starve. At a result, tarving plants are likely to die, clog your filters, and contaminate your aquarium.

Can fish see blue light?

There are some fish species that can identify colors. At the same time, the ability to display colors depends on the depth of the water. Blue light has a shorter wavelength, so fish can easily detect it.

In conclusion 

Is blue light good for fish? The answer is yes. However, you should not turn on the blue light for more than 12 hours a day, the best range is 8 hours of illumination followed by complete darkness.

Besides, you should research and check the fish species and plants you intend to buy to adjust the lighting accordingly and create a good opportunity for the fish species to grow.