Betta Need

How Many Hours of Light Does a Betta Need?

Betta fish do not require a lot of equipment; all they need are a few decorations, a light, heater, filter, and tank. However, each piece of equipment tends to be more complicated than everyone initially thinks. For example, there are many different lighting choices for many different types of aquariums, ranging from T8 bulbs to CFL bulbs to LED, and timed to untimed.

One of the biggest factors in picking a light is how long it will stay on depends on the type of tank you have. Is it planted? Are you having trouble with algae? Each tank will be different and require a different amount of lighting, but you must also take into account your betta’s circadian rhythm.

In this article, we will discuss tropical fish, turning on the light, circadian rhythm, planted tanks, algae, UV light, and night lights.

Tropical Fish

Betta fish are tropical fish, hence their need for a heater, but this also has a direct impact on the amount of sunlight they need. Betta fish generally come from areas ruled by wet and dry seasons instead of winter, spring, summer, and fall.

This means that the amount of light they get every season remains about the same, and it doesn’t alternate throughout the year. In the wild, betta would be accustomed to receiving 12 hours of light a day, and 12 hours of darkness.

With that being said, it is unlikely that you will be able to give your betta this much light. You must be able to balance the amount of light they get with the amount of light that the tank needs. While it would benefit your betta to receive 12 hours of light a day, there are other, more important, factors to consider.

One such factor is consistency. It is much more important for your betta to receive a consistent schedule of light rather than their preferred 12 hours. For example, if the light is not on a timer and you turn it on and off, it is better to establish a certain time each day to turn the light on and off, rather than turn it on at 9 one day, then 8 the next, then 10, and so on.

Turning on the Light

Another issue that is commonly overlooked is turning on the light. While betta fish do have advanced eyes capable of seeing the same colors as we do, their eyes are more primitive than ours.

We can adjust our pupils to different levels of lighting in just a few seconds; betta fish cannot. Most fish take around 30-60 minutes to adjust to different lighting levels.

If you suddenly turn on the light, you could damage your betta. Betta fish are sight predators, so their eyes are extremely important to their wellbeing. Without them, they will be unable to locate food and may starve to death.

The best way to go about turning on the light is to first turn on another light in the room. Turn on another light as an ambient light for about 30 minutes before turning on your betta’s light. This will help significantly, as it is no longer a jump from complete darkness to a very bright environment.

Circadian Rhythm

The circadian rhythm is essentially an organism’s internal clock. It tells the organism when to wake up and when to go to sleep, and it is largely based on lighting. If the lighting your fish is getting is inconsistent, you will start to have some serious issues.

The circadian rhythm is vital to any organism’s functioning (bar a few species that live without light) and has a role in everything from sleep to mood regulation to digestion. The primary issue with bettas and an altered circadian rhythm is digestive issues and illness.

The immune system cannot function properly if the sleep cycle is all over the place and this often leads to sick fish. The water they live in is full of pathogens, but a healthy betta will not have an issue fighting them off.

Even if the immune system is unaffected, digestive issues may occur, which often appear as bloat in bettas. While bloat is easy to cure, if the sleep cycle is constantly altered, it will continuously reoccur.

Planted Tanks

Planted tanks need to have a perfect balance between light, nutrients, and carbon dioxide. Depending on your specific tank, your tank may need more or less light than bettas.

If you have a low-tech tank (minimal or no fertilizers, no carbon dioxide injection), you will likely need less light than what betta wants. However, an issue arises in that bettas are most happy in planted tanks.

It is better for a betta to have a planted tank and less light, often only 6-8 hours per day, rather than a bare tank with a full and constant 12 hours of light. Plants greatly improve water quality and make bettas happier and more energetic.


The only downside to a planted tank is the associated algae. It hitchhikes in on plants in very small quantities and can take months to grow. It can also be present in tap water, especially brown diatom algae.

If you experience as sudden growth of algae, this means that there is either excess nutrients, excess lighting, or excess carbon dioxide that the plants cannot use. In low tech tanks, it is very likely that the excess is light.

The best way to combat algae is to knock down the light to only 4-6 hours per day. If you are dealing with particularly nasty algae, such as black beard algae or cyanobacteria, you may want to turn off the light for 3-4 days in a row.

UV Light

A UV light is often sold as a part of a filter or as a UV sterilizer. The theory behind these is that the UV light will help sterilize the water and kill off certain suspended bacteria and algae. While these have shown to be effective in certain circumstances, they are not essential for the functioning of your tank.

Bettas do not need these to live, and while they may be useful if you have an outbreak of green water, they are not worth keeping around.

Night Light

The night light on tanks is normally fine for most fish, as certain fish cannot see certain colors. For example, a red night light is often used on wood catfish, as they will only come out when they believe it is dark. They cannot see red, so the world appears dark to them, but this gives the owner a chance to view them.

However, betta fish can see all the colors we can, so a night light can be stressful to them. Imagine someone shining a blue light in your face throughout the entire night. Hard to fall asleep, right?

It is best to give your fish darkness as opposed to a night light. Bettas will still see the night light, and it may confuse both your fish and its internal clock, which will lead to a whole host of issues, as previously discussed.

In conclusion, betta fish would ideally have 12 hours of light, 12 hours of darkness, and a consistent lighting schedule. However, this 12 hour of light is often unattainable for the average fish tank, as it may lead to a nutrient imbalance and algae.

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