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What Does Blue Light in Fish Tank Do

what does blue light in fish tank do

Lighting your fish tank is not just about enhancing the appearance of your aquarium. It also plays an essential role in the aquarium’s plants and coral photosynthesis. However, a type of lighting is gaining popularity because of what it brings to the fish and the aquarium in general. I am talking about the blue light, popularly known as the moonlight, which is known to mimic the moonlight and brings a lot of benefits to the aquarium.

But what does blue light in fish tank do? Having blue lighting in your fish tank provides an excellent view to the eyes of those who are viewing your aquarium. But more than the beautiful background it gives to the tank, there are other substantial advantages in having blue lighting in your aquarium, which will be discussed as we go along in this article.


What Does Blue Light Do in an Aquarium?

These blue lights have been popular through the years by most aquarium owners. They are commonly called moonlight, but actually, the primary purpose of this light is to let you see your nocturnal fish at night. So, if you own a fish that only comes out at night or when the lights are off, such as some species of catfish, the moonlight will make them comfortable because they will not be getting that white spectrum coming from the regular lighting.

Another reason for installing a blue light in the aquarium is to copy the moonlight. That is why it is commonly called the moonlight because it illuminates the aquarium while promoting the physical activity of all the species inside. However, blue lighting does not affect the day and night cycle of the fish and the growth of algae.

Upsides of Using Blue Light in the Fish Tank

As an aquarist, you should know that lighting is an essential part of an aquarium. And choosing the right color of light will benefit the fish in the long run. The lighting of the aquarium will have a positive impact on the fish. In fact, it improves the metabolism as well as helps the growth of the fish.

Lighting also contributes to regulating the eating and even the sleeping habits of all the fish in the aquarium. It provides energy and the all-important oxygen, which is critical to fish life. The fish will absorb the dissolved oxygen directly from the water to straight to their bloodstream using their gills.

Meanwhile, proper lighting also enhances the health status of every coral and plant in your aquarium. Blue light is excellent for coral development, but it has also been proven that it is also beneficial for plant growth. Although, there are many different light spectrum which consists of many colors, not all of them are essential to photosynthesizing the plants and other inhabitants found on the tank.
Another upside in having a blue light is it does not increase the water temperature. Regular lighting usually increases the temperature of the water, but in the case of blue light, it is not affecting anything. Meaning, you do not need to monitor the water temperature as it does not affect the hotness or the coolness of the water.

How Does Blue Light Affect Plant Growth

how does blue light affect plant growth

The color of the aquarium plants will pop more when there are blue lightings with the combination of the red lighting. In addition, your plants in the aquarium will absorb the red and blue lights spectrum when compared to other colors. Meaning, the blue and red color bulbs are an excellent option for planted fish tanks.

Plants in the fish tank need blue and red light in order to remain healthy inside. There are many aquatic plants that use chlorophyll which is the green pigments found in all of the plant cells. Chlorophyll is the fundamental of photosynthesis which is the process used by plants to make foods. If there is no photosynthesis, the plants will likely die in the aquarium, will rot, clog your filters, and eventually poison the fish and the aquarium.

In addition, if installed in the aquarium, the blue light will make the plants grow very bushy and leafy. In fact, plants in the aquarium use a specific type of blue light called actinic blue light for their growth. The blue light helps in the growth of the leaves and the stems of the plant. In other words, blue light is essential to the grown of the plants in your aquarium.

Another benefit of having a blue light in the aquarium is its ability not to contribute to excessive algae growth, which we all know is bad for the fish and the aquarium. We also know that algae thrive in lighting sources, but blue light does not help in making them multiply, which is an excellent benefit.


If you are not familiar with what does blue light in fish tank do, you are missing important information about being an aquarium owner. There are substantial benefits that blue light does apart from enhancing the overall appearance of your aquarium. It provides a positive impact on your fish as well as all the plants found in your fish tank. The moonlight, as they are commonly called, will also allow you to see those nocturnal fish and their activities when they are awake at night.

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