Proper lighting in your betta fish tank can really bring out the beautiful colors and fins of your fish to best effect, as well as creating a relaxing environment in your room. But what about the welfare of your betta fish? Should you turn your betta fish light on or off at night? And why isn’t using sunlight to light your betta tank such a good idea?
In this article, we reveal the dangers to Betta Fish of having too much light or too little of the right kind of light, and much more.
Do betta fish like light and is it necessary?
As with all aspects of fish farming, you should try to reproduce the natural conditions in which the fish live. That is the best way to keep your fish happy and prevent them from becoming stressed and susceptible to disease.
Light and dark in the wild environment
Wild bettas hail from the Mekong and Chao Phraya river basins in Thailand, where they inhabit shallow bodies of water, particularly marshes, rice paddies, and floodplains. During the dry season, betta fish live in puddles and survive by eating insect larvae and water-bound insects that alight on the surface of the water.
Most of the betta’s habitat is naturally dark, largely due to the dense aquatic vegetation that grows there and the fact that the water is muddy and often stagnant.
However, betta fish are surface feeders and can also breathe air when needed using their labyrinth organ. That means bettas are generally found in the upper area of the water column, where it is relatively bright in natural sunlight.
Wild bettas are most active during the day, finding their food by sight. When the sun goes down and the environment darkens, the fish go to sleep.
In captivity
Instead, captive bettas are kept in well-lit tanks so their loving owners can see the spectacular colors and beautiful shape of their fish. That’s fine for the fish, as they can see the food on offer and, if they want, they can escape the light and rest among the plants or caves in the tank.
However, like their wild cousins, captive betta fish need to sleep at night. Therefore, you should turn off your tank lights at night to replicate the natural day/night cycle that fish enjoy in the wild.
The easiest way to do this is to turn the tank light on when you wake up in the morning and turn it off when you go to bed at night.
When you go on a trip or work shifts, it’s helpful to have a timer for your aquarium lights. Simply set the timer to turn the tank light on in the morning and off at the end of the day.
Is too much or too little light dangerous for your betta fish?
So now you know more about betta fish light requirements.
But what happens to your betta fish if you leave the aquarium light on too long or not long enough?
too much light
If your betta fish is exposed to too much artificial light, some problems can arise.
First, if your betta fish lights up too much, he may be overstimulated. Although bettas tend to nap for short periods during the day, overstimulation causes the fish to be more active for longer periods of time. That can cause stress for the betta fish, which in turn leads to health problems and vulnerability to disease or parasite attack.
Also, too much light can cause your betta fish to stop eating. Bettas can be finicky, and the stress of overstimulation often causes a lack of appetite in these finicky fish.
Remember that betta fish are creatures of habit, eating during daylight hours and sleeping after dark. If your betta fish lives in a perpetual daylight environment, its biological clock won’t know when it’s time to eat and it may stop eating altogether.
not enough light
So what happens if you deprive your betta fish of light?
Just as your betta tank should have a filtration system and heater, it should also have lighting. If your betta fish is kept in very dim or dark conditions, it may lose some of its beautiful, vibrant colors.
Also, if you’re hoping to breed from your betta, you should know that spawning is much less likely to happen in a very dark tank.
Why not use natural sunlight instead of artificial light?
You may think that placing your betta’s tank on a window sill or somewhere where it gets a lot of direct light might be a good solution to your lighting dilemma.
Unfortunately, that’s not a good idea.
This is why.
algal bloom
Too much direct sunlight hitting your betta’s tank will encourage an algae bloom.
While the algae isn’t dangerous to your fish, the green slime will quickly cover the glass, marring the look of your tank and making the entire environment look unsightly. Algae also grows on decorations, the substrate, the filter unit, and even on all living plants.
Algae are aquatic organisms that generate the nutrition they need through photosynthesis. Although algae are a nuisance, these organisms do have some benefits in that they remove harmful substances, including nitrates, from your tank water.
Also, any species of fish, including bettas, collect algae as part of their daily diet.
I keep algae growth in my tanks in check by keeping algae eaters including snails and Amano shrimp, both of which make good tank mates for bettas.
temperature shock
Bettas are extremely sensitive to changes in temperature and can go into shock if the water in the tank gets too cold or too hot.
If your betta fish tank is in a place where the sun shines all day, the temperature in the tank can become too high very quickly, which will definitely stress your fish and could even kill it.
How Much Light Does a Betta Tank Need?
As a general rule of thumb, you should have 1 watt of light per gallon of water or less for LED lights and 1.5 watts of light per gallon of water for fluorescent lighting.
In the wild, a betta’s day is generally shorter than ours. That’s because the dense aquatic vegetation in their environment blocks much of the natural sunlight. So, to mimic that pattern in the captive environment, your betta should have eight to 12 hours of light a day, followed by 12 to 16 hours of darkness to replicate night.
What about the colored lights?
Many aquarium lights come with a range of built-in color and special effect options, which you can use to great effect when designing the look and feel of your betta tank.
Colored lights don’t affect your betta any differently than white lights, as long as you follow the day/night routine.
Watch out for reflections!
Male betta fish are very territorial and aggressive towards other males. The sight of your own reflection can cause your fish to attack, mistaking your reflection for a male intruder.
Although your betta’s flare may seem impressive, it is actually a very stressful experience for your fish. These tips will help prevent glare that artificial light sometimes causes.
- Turn on your betta tank light only when the light in your main room is on. Reflections occur most often when your aquarium is lit from the inside and outside lights are off.
- Try to introduce the light from your tank gradually to your betta. Turn on the light for a couple of hours a day, increasing that time until your betta remains calm and shows no signs of aggression.
- Place aquarium paper on the outside of the glass to help prevent reflections on the inside.
If there is a particular area in the tank where your fish turns on or shows aggression, I find that placing a bushy plant in front of the glass often solves the problem.
Can betta fish see in the dark?
Since wild bettas live in a dark and murky environment, you may be wondering if your fish can really see in the dark. To answer that question, you first need to understand a bit about how fish vision works.
color vision
Betta fish can see virtually the same colors as you, although it is believed that the tones and hues that the fish see are slightly different from ours. Also, some bettas cannot see red light and therefore those individuals can be described as colorblind.
Interestingly, fish that live in deeper water than bettas cannot see the color red. This is because each color in the spectrum has a different wavelength and colors are absorbed by water at different rates. Red is first absorbed by water, so deep-sea and river fish species cannot see the color red.
How do betta eyes work?
So bettas’ color perception is very similar to yours, and there are similarities in the way their eyes work, as well as some differences as well.
Bettas can precisely focus on a single object, which many other species cannot do. However, unlike its eyes, your betta fish will see a blurred, contrasty image, which will allow the fish to differentiate the object extremely effectively through a high contrast image.
blinded by light
Unlike you and me, bettas cannot rapidly dilate and contract their irises. It takes 30 to 60 minutes for your fishy friend’s iris to adjust one way or another.
This is why you should never turn on your aquarium light without first turning on another light in the room. Suddenly turning on the tank light in a dark room could damage your betta mate’s eyes and can stress him out.
monocular vision
Betta fish have monocular vision. That means each eye sees a different image. Humans have binocular vision, which means they can use both eyes to focus on a single object.
Creatures with binocular vision are likely to be predators and usually have forward-facing eyes. Animals with monocular vision are generally prey species and have their eyes placed on the sides of their heads.
Betta fish are predators, but they are also prey. So while bettas’ monocular vision helps them stay alert to potential danger, the ability to focus on a single object allows the fish to be extremely efficient predators, too.
Night vision?
So while your betta fish has remarkable eyesight that helps keep it safe from predators, as well as allowing it to hunt for insects on the surface of the water, it can’t see in the dark.
Your betta friend can’t see in the dark, but he has another amazing ability that helps him orient himself and protect himself in his surroundings when the sun goes down.
Lateral Line: Your Betta’s «Sixth Sense»
Look very closely at your betta fish and you will notice a series of small holes in the scales that run along the sides of your fish.
The “ lateral line ” allows the betta fish to sense movement, vibrations, and pressure changes in the water.
The fish use that information to estimate the size of an object in the water near them, especially if that object is moving. The betta fish’s brain then processes that information to decide whether to run away from a potential aggressor or take evasive action to avoid hitting something.
So even though your betta fish can’t actually «see» in the dark, it uses its amazing sixth sense to stay out of trouble and avoid colliding with the sides of the tank and structures within its surroundings.
final thoughts
Your beautiful betta fish has extraordinary eyesight. It can see the same colors as you, it can focus with deadly precision on its prey, and it uses its sixth sense to keep it safe in the dark.
Bettas need a clearly defined day and night schedule to be happy. Your fish will be busy feeding and exploring during the day, while at night, your betta fish needs darkness in order to sleep and rest.
If you provide that to your betta partner, he will be a happy and long-lived fish.
