Do Betta Fish Need Sunlight? (Explained!)

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Betta fish naturally inhabit ponds, streams, and marshes in southern East Asia. They live in a tropical part of the world where the sun shines brightly for long period each day.  Bearing this in mind, it might seem like a good idea to try to light a Bettas aquarium with natural sunlight.

A Betta aquarium does need light, but this should not be sunlight.  A Betta aquarium lit directly and solely by sunlight will suffer from blooms of algae, temperature swings, and a chance the Bettas eyes will be damaged.

Do Betta fish need sunlight?

It is important that a Betta fish tank has light.  Bettas do require a defined day and night cycle.  They need a time of the day to be active and a time of the day to rest, even sleep.

Whilst Betta fish do need light, it is much better to provide that light from a dedicated aquarium light located above the tank. By using an aquarium light rather than the sun, the aquarists have control over the amount of light and the intensity of the light.

I like to use proper aquarium LED lights for all the tanks in my fish room.  I ordered a couple of these lights from Amazon, and they worked well for my Bettas.

There is no reason to use natural light to light up a Betta tank. In fact, natural sunlight can be harmful to a Betta tank.

Why you SHOULDN’T light a Betta tank with natural sunlight?

The problem with using the sun to light up a Betta tank is the sun is unpredictable.  One day it might be overcast with very little light, the next the sun might be beaming in through the windows.  Betta fish don’t like unpredictable conditions. 

Whilst they are undoubtedly hardy fish, they do like their water parameters to be stable, and a tank that is lit by natural sunlight is also often heated by the same sunlight.

When the sun shines through a window into a tank, the water temperature increases.  Adding this to the fact we often keep our Bettas in small volumes of water, the temperature can rise significantly in a short space of time. 

Bettas like their water to be around 78°F (24.5°C) and although they don’t mind if the temperature wanders a little above that, they don’t like it to swing.

The other major problem lighting a Betta tank using sunlight is the algae will be uncontrollable.  Algae is always a factor in our aquariums and whilst algae isn’t bad for a Betta aquarium, it does spoil the way the aquarium looks.

I can assure you from personal experience, a Betta tank on a window ledge or too close to a window will be an algae farm forever!

I once had a long tank that fitted perfectly along a window ledge, and I thought it would look amazing in the window with a Betta living in it. To be fair it did look great, for about a week, then every surface was covered in green and brown algae!

Does a Betta tank need light at all?

As mentioned above, Bettas definitely benefit from the addition of an aquarium light above their aquarium.  

Experiments have shown that Bettas who are kept in aquariums and subject to a regular day/night schedule were generally healthier and more active than those kept with either no light or a light switched on for 24 hours a day.

Bettas do actively rest at night and that seems an important part of keeping them healthy.

What sort of light does a Betta need?

If I am honest, I don’t think it matters to the Betta too much what sort of light it has.  

A modern LED light fitting is going to cost less to run and won’t give off a lot of heat, which can raise your Bettas water temperature, but a standard light bulb will work just as well if that is what you have available.

More importantly than the type of light that is used, is how that light turns on and off.  It is extremely important to have a Bettas tank light connected to a timer. You can buy wifi-controlled timers like these ones on Amazon for around $10 for 2!

When the light is on a timer, you don’t have to worry about remembering to turn it on and off each day.  You also don’t have to worry when you are on vacation, or if you have to travel for work.  You know the light will come on and off every day at the same time.

As someone who has accidentally left a Bettas light on, then gone on vacation and had the light running 24 hours a day for a whole week, I can assure you my Betta didn’t like it, and every surface in the aquarium was covered in algae.  If you do nothing else, make sure your Bettas light is on a timer!

How long should a Bettas light be on each day?

There are no hard and fast rules about how many hours of sunlight a Betta needs every day, but I shoot for 8 to 10 hours.  8 to 10 hours work for my Bettas, and the live plants I have in my Bettas aquariums. 

Much less than 8 hours and the plants will suffer, much more than 10 hours and I have found algae starts to take advantage.

You can also split that time. So for instance the Bettas light could be on for a couple of hours in the morning before you go to work, then the timer switches it off.  Then have the timer set so the light comes back on before you return home, and you can enjoy another 6 hours of Betta light in the evening.

Many people make the mistake of their Betta light coming on at 9 am, then off again at 7 pm, meaning they almost never get to enjoy the tank fully lit because they are at work.

My final thoughts on ‘Do Betta fish need sunlight?’

Whilst Betta fish undoubtedly need light, it doesn’t have to be sunlight. In fact, it really shouldn’t be sunlight as sunlight is uncontrollable.  Betta fish do really well when they have a routine, and the Betta aquarium does best when we can control the amount of light it gets.  

Believe me, a Betta tank light purely by the sun will be an algae farm that you will never get control of.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James