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Can Fish See Blue Light

Fish are very sensitive animals and as a fish tank owner, you love to take care of your colorful pets. The idea of using Blue Light to fish tank can give a natural and underwater moonlight experience, but is it good for fish? Can Fish See Blue Light?

We are here with all of our research and will enhance your knowledge with this blog with all of our severe conclusion.


Can fish see blue light?

Yes, a lot of fish variety can determine color usually from their environment only using their developed eyes just like a human. The visibility of colors also depends on the depth of the water, the blue colors are having shorter wavelengths although they can penetrate deepest into clear water which is why it is easily recognizable by the fish.


Does blue light harm fish in an aquarium?

Not only the blue light but any light during the night is harmful to the fish. Fish work/play at a scheduled time and they need proper darkness of a minimum of 8-12 hours dark period for a night of healthy sleep.

If it is not followed, then the fish can have stress-causing by light and sleep deprivation might bring behaving abnormal, which will lead to the sickness of your fish.

In the case you are having nocturnal fish in your tank, then you can use blue light all night so you can keep your eyes on them. And the light also creates a moonlight experience so they can eat, play, or swims around the fish tank.


Does blue light also bother goldfish?

As the nature of goldfish, they don’t need any kind of lights. They love full dark so they can sleep better and be full- energetic in the next day. The daylight is enough for the fish and their healthy lifestyle. They do not need any artificial lights during the night.


Does blue light affect the fish’s eyesight?

Yes, the lights cause stress to the fish, especially the goldfish can have great retinal stress. When the blue light keeps on in the night on the regular basis, like for a week, then the fish will get apoptosis, which later leads to death.

Many people try to keep lights on at a very low- intensity, but they are not aware that they will also cause cell death in the retina.

But the nocturnal fish like big eyes, Squirrelfish, Soldierfish, Porcupinefish, Scorpionfish, Snappers, and many other varieties don’t have any reaction to blue lights.

In this case, mainly LED lights can be used because they can be programmed for the intensity on a timer basis, which helps keep both fish as well as plants healthy.


Does blue light affect the fish’s reproductive?

Different fish varieties need a different color for their proper growth, especially in the aquarium. Wrong lighting also affects the reproductive hormones. So we have to find out which type of color they prefer?

In the case of blue light, it does not affect any of the fish varieties even though this color boosts their growth. According to 2004 data, the aquarium fish verities like carps, rotans, crucian carps, guppies, and silver carps develop very well in the blue lights.


What is the role of blue light for plants and algae in a fish tank?

Relationship of plant and blue light

Blue light is directly absorbed by the plants in order to produce chlorophyll (the green pigment present in plants). This light also boosts plants growth.

You may have noticed the fish tanks, especially those contain nocturnal fish, haves blue lights and their plants have stronger stems and leaves. Some other lights like the red color lights also help plants in their initial stage of root growth and period of seed germination.


Algae growth in blue lights

In the case of algae, we all know it is autotrophs (who produce their own food) so they are directly dependent on light. The greater the light will be the faster it develops. And the rest of the essential nutrients they can absorb from the fish tank water.


What are the benefits of blue lights in a fish tank?

The blue lights in fish tanks create multiple benefits for the environment. Blue lights provide very soothing effects that keep fish very calm.

As we have mentioned above, blue lights give a moonlight effect to the fish at night. Blue lights may give relief to the stress caused by the high intensity of the daylight. They will also make fish feel comfortable and give them the presence of a natural environment.

In addition, they can make it easier for us to see and give a pleasant view to our eyes. We love to see the movement of our colorful fish and the blue lights give the best view rather than any color.

Blue lights do not warm up or increase the temperature of the fish tank water. Other lights or LED lights with high-intensity lights will increase the temp and control by automating their intensity timing.


What is the proper timing for the light in an aquarium?

Proper light of 10-12 hours is essential for both fish and plants. Blue lights are more effective than any other lights including white lights. We have already examined the light’s benefits as well as its drawbacks for both the diurnal and nocturnal fish.

We should take care of the lighting period, although peoples have different choices and different fish have different habitats of living. So, we have mentioned below some conditions of lights through a table.

Stocking level

Hours of light

Tropical fish only

8-10 hours daily

Tropical fish & plants

10 hours daily

Heavily planted

12 hours daily

Coldwater fish & plants

8 hours daily

Coldwater fish only

8 hours or less daily


Hope we have cleared all your queries through this article regarding “Can Fish See Blue Light?” and providing you with which is best for your aquarium. If you have any unanswered questions or want suggestions for the products for your aquarium then please leave your message in the comment section.



1. What will be the lightning period for only fish tanks with very plants?

The lightning period for a fish tank is at least 8-12 hours in a day.


2. Can Fish Hear You?

Fish have very quick reflexes, they can hear and sense sound through their otoliths (ear) and also through vibration through the water.


3. What happens if we choose green light rather than blue light

The green light in the fish tank will eventually increase the growth of algae and which is later hard to control and increase the level of ammonia and also makes fish unable to breathe by lack of oxygen.


4. What happens if we choose red light rather than blue light?

Red lights in the fish tanks aren’t a better idea if it’s fewer plants in your aquarium. It makes it difficult to watch some fish for owners. It gives to support the development of algae and also makes plants grow taller which creates difficulty in maintenance.

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