Can Betta Fish See In The Dark?

Betta fish are beautiful fish you would enjoy having in your fish tank, even if they are a little aggressive (beware of letting it see its own reflection!). If you are thinking of adding one to your aquarium, you might be wondering if betta fish can see in the dark or how much it can see in the dark.

Although a betta fish’s eyesight is good for very short distances, in general, its eyesight in the dark is very weak due to the slow function of its eyes’ irises. Compared to a human’s eyesight and iris function, a betta fish’s is much weaker.   

Let’s read on to find out more about how these colorful fish see and what exactly they can see.

How Do Betta’s Eyes Work?

Being able to see clearly is of paramount importance to any wild animal because this sense helps to keep them safe and healthy. This is particularly true for fish like the betta fish because they are sight-based predators. This means that betta fish hunt in the wild by seeing its prey. Its sight offers it a chance to eat. If the betta cannot see its prey, it doesn’t get to eat. 

A betta fish also has monocular vision due to its retinas having rods. This means that each eye can see in two different directions at the same time, unlike human eyes, which work together to see one direction at a time. Monocular vision also allows the betta fish to see and determine colors. A betta’s monocular vision doesn’t help it to determine depth perception, though.

By not having good depth perception, you might assume that your betta will bump into everything in its tank. Surprisingly, it doesn’t bump into anything. Betta fish have pressure sensors along their sides that help them to navigate through the water successfully by telling it how close they are to something. This prevents it from bumping into the things in its tank.   

The Betta Siamese fighting fish, Betta splendens Pla-kad ( biting fish ) Thai. (Halfmoon fancy white Red betta ) in motion on abstract bubble blue background

Can Betta Fish See In The Dark?

The biggest reason betta fish do not see well in the dark is due to their poor iris functionality. The iris is the part of the eye that decides how much light to let into your eye. If you have a big iris, more light is let in. If you have a small iris, like the betta fish, less light is let in. The biggest issue with a betta fish’s iris is how slow the iris reacts to let more light in so the fish can see well.

Betta fish don’t do well when a light is turned off abruptly due to its slow iris functionality. Basically, its irises cannot adjust quickly enough to allow them to see easily. This actually can blind it for a period of time. On average, with sudden light changes, it takes the betta’s iris the same amount of time to open up enough as it takes the sun to set in the evening (between 30 and 60 minutes).

One option to offer your betta fish a safe, unstressful way to have both darkness and light is to heavily plant your tank. By having many areas of plants in the tank, your betta will have a filtered light that allows it to see more clearly. This will also allow your betta’s eyesight to adjust to brighter areas of the tank more gradually so that this doesn’t damage its eyes.

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Do Bettas Like Being In The Dark?

Betta fish like the dark when they are trying to sleep. During the daytime, they want lots of light because this is when it is more active in their tanks. Light and daytime will signal to your betta fish that it is time to hunt for food, eat, and explore its tank. Since they cannot see well in the dark, they will not be able to do these things and will just sleep because they are bored.

Bettas need a clearly defined daytime and nighttime to be physically and mentally well. It needs the light to expel its energy and eat, but your betta fish also needs the darkness to rest and sleep. The natural environment of a betta fish will have both light and dark, so your tank should replicate these conditions as well. 

Only having a dark tank would stress your betta fish to the point that it might become unhealthy. Stressing out your betta can make it more susceptible to infections, depression, or immune weaknesses. It is important to remember that your betta fish only truly likes being in the dark when it is trying to rest, relax, and sleep.

Can Betta Fish See Their Food In The Dark?

A betta fish will not be able to see its food very well in a dark environment as the food will blend in with the environment in a way that your betta fish cannot see. Some people debate that bettas can see the outlines of fish food if a small amount of light is available in the tank. Fish food is very small, so it is unlikely they will actually be able to see these vague outlines. 

Even with the pressure sensors along its body, there is no evidence to say that they are sensitive enough to detect those small food particles. A betta fish’s poor eyesight relies on how much light it is able to filter, so the more light, the better. Without much light, they won’t be able to see its food.

You should feed your betta fish twice a day: once in the morning and once in the evening. There will be lots of light during the morning feeding, so you won’t have to worry if it can see them; however, during the evening feeding, the light is low or gone. Make sure you keep the tank light on in the evening so your betta can see its feed so that it can eat well.

Can Betta Fish Sleep In The Dark?

Betta fish really like sleeping in darkness as it is difficult for them to sleep during the daytime.   During the day, it will be exploring its tank and hunting for food. Darkness mimics the natural day and night pattern of wild bettas, so this is how it determines what to do during the cycle of a day. Nighttime and darkness are when bettas expel the energy that they gain by sleeping.

Chances are high that if you turn off your tank light during the day, your betta fish will just go to sleep as this is its preference for sleeping. Daylight signals a betta that it’s time to hunt and explore, and darkness helps to relax it to sleep. Although your betta fish can nap some during the day, it is better able to rest while it is dark.

Total darkness will actually help your betta fish to sleep better. At night, not only should it be in a dark room, but you should also turn off its tank lights to ensure that your betta gets the absolute best rest so it can be prepared for tomorrow. An unrested betta will become stressed and unhappy, so it is important to allow it the best sleep possible.

Is It Bad For Betta Fish To Be In The Dark?

Your betta fish needs, at minimum, ten hours of light a day. You should never leave it in the dark for an extended amount of time (exceeding eight or ten hours). The bright light will allow your betta to explore its aquarium confidently and see its food easily. Remember, your betta fish cannot see its food in the dark, so it needs this light to be able to eat the amount it should.

In general, yes, it is bad for betta fish to be left in the dark. They will not be as active as they should be without light, which can result in health problems for your fish. Its colors can diminish, showing just how depressed the betta has become without light to engage it. This sort of stress can also open your betta fish up to a number of other possible illnesses.

It is important, however, that you do not allow your betta fish’s tank to have too much light. Being exposed to light too often can result in overstimulation. Overstimulation can cause your betta to be even more active than normal during this time. This can cause stress for your betta, which can make it vulnerable to other diseases or attacks by parasites.


There are many things to learn about taking care of your betta fish, but worrying about its eyesight shouldn’t be a concern for you. Even though its irises react slowly to sudden changes of light, they will adjust and allow your betta to see clearly. By providing adequate light in your fish tank, you will ensure that your betta fish has everything that it needs to find food and expel energy. Mimicking the natural cycle of a day will ensure that your betta fish is happy and healthy in all aspects.

About the author

Hey there! I'm Antonio, the passionate owner and chief editor of Betta Care Fish Guide. With over half a decade of hands-on experience, I've become your go-to expert for all things betta and tropical fish.

Over the past 5 years, I've not only kept bettas and other tropical fish but also connected with a diverse network of hobbyists, seasoned fishkeepers, and even veterinarians.

Now, I want to help other beginner fish keepers who had the same questions as me when they were just starting out! So they can save themselves a ton of time and keep their fish happy and healthy!