Home Aquariums Can I Leave A Blue Light On In A Fish Tank?

Can I Leave A Blue Light On In A Fish Tank?

by Lucy

Taking on the responsibility of keeping an aquarium healthy, however fun, is not a task to be taken lightly. It’s best to prepare yourself and a fish tank before you adopt any fish.

And, it’s not only a good idea to read up on the kind of essential items to keep your fish healthy in fish tanks, but an absolute must to research their diet and upkeep too. Foresight is better than hindsight for your pet as well as your pocket. 

So, can you leave a blue light on in a fish tank? No, you should not keep a blue light or any other colored light on in your fish tank through the night. Unless you have nocturnal fish, they depend on light cycles to maintain their sleep cycle. Leaving a light on at night will disturb this cycle and result in sleep-deprived and stressed fish.

Read on to find out which kind of light is best for your aquarium and why it’s a bad idea to keep the aquarium lights on through the night.

Why You Can’t Leave The Light On In A Fish Tank

It doesn’t matter whether you use blue light or red or green; you must give your fish total darkness through the night. Many aquatic experts claim that fish behavior, including feeding, mating, and aggression, is affected by their sleeping patterns. 

Fish don’t have eyelids, so you can’t tell when your fish are asleep. But that doesn’t mean that fish don’t sleep. Some fish need to keep swimming to have water move through the gills to keep the oxygen levels steady.

So when fish sleep, they don’t hold completely still; some may slow their activity and metabolism levels to get rest, yet stay alert of any danger in their surroundings. 

Most fish are diurnal, that is, sleeping in the night and active in the day. So, they do follow the light cycle. Fish follow the sun’s process; hence they wake when the sun rises and sleep when it sets.

In the wild, fish have no source of lighting in freshwater or seawater through the night, and it is during these hours that they rest. Following the same routine, fish need the same number of hours in darkness in aquariums to maintain their energy levels. 

What Kinds Of Light Are Best For Fish Tanks?

You have to realize that lighting in the fish tank doesn’t only impact the fish. It affects the plant life in the fish tank too. In general, it is said that fluorescent lighting is suitable for fish tanks. You can get several options, from compact fluorescent bulbs to LED lights (these ones are my favorite for my fish). 

But, in recent years, LED lighting has gained much popularity. There are many reasons for the preference of LED lighting to all other kinds of lighting available in the market.

LED lighting is inexpensive and lasts much longer than your fluorescent bulbs. Furthermore, it does not hurt your fish or their vision in any way. And, it does not negatively affect the plant life in your aquarium either. 

What Kind Of Color LED Lights Are Best For Your Fish?

There are many different colors available in LED lighting. You will find bright yellow light, as well as cool white light. Then there are color variations available in the market too. You can get blue, red, and green light too.

White/Yellow LED Light

The full-spectrum white light is the most commonly used by fish owners. But, it isn’t lighting that will help your fish or the plant life in your aquarium and may result in more algae in the fish tank.

Blue LED Light

Blue LED lighting creates a calming ambiance in your aquarium. Many fish enthusiasts say the blue light serves best as a transition light between light and darkness. So, you can use the light in the evenings to help your less curious fish to come out of the hiding spots as blue light mimics the moonlight. 

Blue LED lighting, also known as moonlight blue bulbs, support your fish tank plants and help your nocturnal fish to feed. However, even this subtle light should be switched off at night so that your fish can sleep soundly.

There are, of course, exceptions to this rule. If you fish are nocturnal, a blue light will be perfectly acceptable to give them, just enough light to see without tricking them into thinking it’s daylight.

Red LED Light

Many fish lovers claim that red light is bad for fish. But there is no scientific research to support this claim. Water absorbs red light more readily than blue or green light. So, yes, red light does help your aquarium’s plants.

The plants use light for growth and photosynthesis. And, it helps with the pigmentation of your red plants too. It will make your red plants healthier and far brighter than with yellow light. It may also encourage your shy and bottom-dwelling fish to come out and move around.

It is said to do wonders for fish like the kuhli loach and catfish. But, algae use red frequency for photosynthesis. Hence, you have to be extra careful about the number of hours you make use of the red light in your fish tank. Don’t leave it on constantly.

Green LED Light

Here is a color that many fish lovers are unsure about, but it does seem that fish themselves are keen on the green.

Another element of green light that stands undisputed is that green light tends to attract more fish. You see, anglers often use lighting to attract fish for fishing. No other lights attract as much fish as a green light. But there are minimal studies to prove that green lighting is suitable for fish when it comes to fish tanks. 

Yet, animal lovers claim that the color green itself seems to be the color that can only do good. It also has a very positive effect on the human psyche for its peaceful and vibrant hue.

Hence, people are recommended to have more green paint on the walls of their homes or more green plants and decor in general. And, if you are to apply the same rule to fish, then it stands to reason that green lights in the aquarium would be suitable.

Related Questions

Now, to answer some of the commonly asked questions that many fish parents tend to fret about.

What Light Is Best For Fish?

There is no simple answer to this question. Many people use lights for aesthetics. But if you worry about the well-being of your fish babies, too, then it’s best to go with a blue and white combination. The blue light will help your fish and underwater plant life thrive.

But if you do your research right, you may use a high-quality red or green light that emits high-quality diodes, which will then be equally significant for the fish and plant life. And if you can’t afford to go with an LED light where the light-emitting diode is top quality, then you might as well go for the T5 fluorescent bulb. 

Do Fish Like The Dark?

It isn’t a matter of preference. Just as fish need light for them to function correctly, so they need darkness to rest. Nocturnal fish don’t need light at night either, so if you have both diurnal and nocturnal fish in your tank, it’s still best to leave the light off.

When you study fish in their natural habitat, whether fresh or saltwater, they function perfectly fine by day when there is light and do just as well in the night when there is total darkness. 

Fish don’t just go by vision. Animals, including fish, live their lives more by instinct and other senses than by eyesight alone. Some fish even have pressure-sensitive organs by the side of their bodies that give them a pretty good idea of the nearby fish and other objects around them from the vibrations in the water.

Can Fish Hear You?

There is a consensus that fish do possess the ability to hear. Fish can sense sound through their lateral lines and their otoliths (their ears). Fishes naturally do not have ears like most mammals.

They have a specialized hearing apparatus that allows them to hear sounds underwater. They can listen, and even respond, to the human voices that they listen to every day. 

Up Next: Do GloFish Need Light At Night?

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