Can Betta Fish See In The Dark?


Being one of the most beautiful fish to have, betta fish make an impression that they are aggressive and add vibrance to the aquarium. Still, they are a great species to have. While buying and starting to have them in your aquarium, some of the most popular questions regard their vision.

Can betta fish see in the dark? How well can they find food in darkness? Do they need light? We will answer all of these questions in the article below.

Betta Fish’s General Vision

First thing first, their general vision is not that good. The eye structures more or less resemble that of most mammals, birds, and other terrestrial species. That said, unlike human binocular vision, betta fish have a monocular one.

It makes them extremely bad at perceiving depth (i.e., how far objects are away from them). That means their eyesight is even worse than ours. So their vision is not even good to start with, let alone seeing in the dark.

Another contributing factor to this poor vision is their tiny irises. FYI, the iris is like the shutter of the eyes, which controls how much light can go into the retina. The smaller the iris is, the less light an eye can perceive at a time and see in darkness.

Can Betta Fish See In The Dark?

The short answer is: Not very well. Although these creatures can still see vaguely in the dark, their vision is not so great at doing so. It is due to the nature of their eyes, which is a lack of functionality in the iris.

How Well Can They See In The Dark?

At the moment, you might ask how their natural habitat is muddy water, yet they don’t excel at seeing in the dark. While it is true that bettas live and can still see in murky water, it’s not necessarily true for total darkness.

If you leave a betta fish in the aquarium, give it food and then turn the light off to go to sleep, it won’t stand a chance to find the food. In their natural habitat, they follow a day-night cycle, in which they use the ambient light of the day to feed themselves.

However, they can still use their sensors along their body to deal with the darkness. Scientists call these “lateral lines,” allowing them to feel water pressure around them to avoid dangers and obstacles.

Then, when it’s dark, they tend to rest up and have a good night’s sleep just like we do.

Betta Fish’s Vision In The Dark Explained

As we explained, the anatomy of betta fish limits its ability to see well in darkness. Even though their natural habitat is murky and muddy rice paddy fields, they still prefer living in clean, crystal clear water.

The iris is a crucial part of any eye’s structure on animals. This organism allows the eye to adapt to changes in light intensity by changing its openness. For example, suppose there’s sufficient light around. In that case, it will shrink to limit the amount of light entering our eyes, preventing damage or dazzling effect.

On the other hand, when it’s dark, the iris must open to its fullness so that the eye can gather as much light as possible to see.


Since bettas have tiny irises, their openness is already limited. While this is no problem in daylight, it restricts the amount of light their retina can receive in the dark, even at its widest.

What’s more, their iris is extremely slow, which means its speed to open and close in adaptation to light changes is terrible. It makes them less likely to be as adaptive as some species that excel in seeing in both daylight and darkness, such as humans.

It is not something to be concerned about since bettas are diurnal creatures that live in stagnant water. Direct sunlight is a more significant threat for them than darkness, as in nocturnal animals.

Can Betta Fish Be Kept In The Dark?

After a couple of days with them, you should notice that these creatures are pretty active when it’s daytime. However, they will become much quieter and more reserved during nighttime, when they usually fall asleep.

Hence, a quality environment for them should be a balance between day and nighttime. Artificial light is not necessary, but natural and ambient light should be enough for them.

What’s more, they don’t even like living in the dark. As we discussed above, these creatures have their biological clocks, similar to humans. Do you like living in the dark all day long, day after day? If no, then maybe that’s their answer too.

Betta’s Vision Compared To Nocturnal Animals

As a trade-off, being a diurnal fish makes them worse at seeing in the low light situation but better at distinguishing colors. The retina of most animals’ eyes comprises two types of cells: rods and cones.

The rods facilitate the eye’s ability to see colors, and the cones help perceive monochrome vision. In diurnal species, both these cells have vast numbers, so they can easily detect different patterns and colors for easier hunting in daylight.

With nocturnal species, their number of cones is higher than the number of rods, so they excel at seeing in the low-light condition, but only in monochrome and not that good in detecting colors. The point is, darkness already limits the range of color emitted with light, so the function of the rods is restricted, and they become unnecessary.

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In Conclusion

That’s all about the question, Can betta fish see in the dark? To wrap up, they are not susceptible to light and prefer a natural day-night cycle just as we do.

Remember not to feed your colorful fish in the dark since they won’t be able to find food. Last but not least, always turn the light off when it’s night and wish them a good sleep.

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