Can Betta Fish See in The Dark and Do They Need Light at Night?

Betta fish make for a beautiful addition to any aquarist’s home. With their beautiful coloration, unique behaviors, and relatively easy care regimen they can be fun fish for the intermediate fish keeper.

One thing every aquarist should know about is how their fish function between day and night, as sleep is a vital part of any fish’s long term health.

Questions regarding how fish manage to survive at night, both in the wild and in our homes, are certain to come up for the curious.

If you’ve ever asked yourself the question “Can betta fish see in the dark?” read on to find out the answer to this and more!

Can Betta Fish See in the Dark?

Betta Swimming in a Dark Fish Tank
Betta Swimming in a Dark Fish Tank

The answer to this common question is that while betta fish can see in the dark, they have relatively poor vision due to their slow iris functionality and monochrome vision.

Even humans and other fish can be said to have reasonably better vision in a dark area than bettas, having adapted night vision to survive more during different periods of the day night cycle.

The primary reason for this is that bettas are not nocturnal animals, and therefore have not adapted to source food in complete darkness.

They are a tropical fish that has to find food during the daytime using natural sunlight that filters down through the water column, even in relatively murky water.

NOTE

Wild bettas live their life cycle in the bright, sunny waters of the tropical Southeast such as Thailand and Malaysia.

As such they’ve evolved to depend primarily on differences in light and color to detect their prey.

As a result they have fairly good color vision compared to other fish, which also comes in handy when putting out mating displays and fending off other bettas in territorial matches.

Some Betta Background

Known commonly also as Japanese or Siamese Fighting Fish, the Betta splendens that most people think of has been carefully bred into its current form over the course of hundreds of years.

Making their way to the West took until around the 1600s after passing through the hands of the Siamese royal family and into the minds of scientists and breeders.

FACT
Bettas are a member of a group known as Anabantoidei, or labyrinth fish. These fish have all adapted to low-oxygen waters or surface breathing through gulping air and holding it in the complex labyrinth organ that they share.

Labyrinth Organ

Betta using it’s labyrinth organ

Being from a semi-dry, variable environment, bettas have also had to adapt to being out of water for periods of time.

Thanks to the presence of their labyrinth organ, they have gained the ability to breathe air from the atmosphere.

In fact, bettas can survive out of water for as long as 5-6 hours at a time, which helps when they jump out of one rice paddy and can’t immediately land in another!

History

Fish keeping bettas began with children collecting them from their natural environment, which includes small warm puddles and rice paddies.

These bright, aggressive fish would be gathered and used competitively, both for their beauty and fighting prowess.

The scientific name itself, Betta splendens, denotes this origin, meaning “beautiful warrior” which still stands today.

How Betta Fish Eyes Work

Betta Fish Facing Front
Betta Fish Facing Front

Betta fish vision differs from what humans would consider the norm. While our eyes work together to produce a single, cohesive image through what is called binocular vision, betta fish see with each eye individually.

This is called monocular vision, and it means that while it can focus on an object around a foot away, they have difficulty getting both eyes to settle on one thing.

Betta Eye Shape

Unlike the eye of most terrestrial vertebrates such as humans, in which the shape of the iris is able to deform and focus (typically as we squint) the betta fish retina stays in one shape and cannot be focused.

This means that betta fishes also have poor depth perception, leading to a reliance on natural light to help identify objects around them and locate prey.

What this means for the home aquarist is that the presence of artificial light is key to helping your fish see its food and feed itself.

Monocular Vision

The diurnal animal retina has evolved over time to use a greater number of rods than cones to detect colored lights and provide color vision.

Seeing as betta fish are more active in the day time than at night, this makes sense for them.

While they may have a hard time with seeing objects and food at a distance with their monocular vision, their ability to distinguish color may be far greater than ours!

NOTE
Unlike bettas, the eyes of deep sea fish are greatly adapted to see in the dark.

Unlike betta fish vision which can take in red, blue and green, that of these high pressure fish has focused primarily on the use of red light which is more available at these low depths.

The Iris

The betta fish has what can be considered a slow iris action. This poor iris functionality means that the eye cannot adjust swiftly to changes in ambient light or color, and as such the fish will likely act shocked when this happens around them.

To prevent potential shock and harm to your betta, always avoid too much light at one time by changing light slowly.

The Lateral Lines

As with most fish, bettas have evolved an additional method for detecting and maneuvering through their surroundings. Called lateral lines, this “sixth sense” for fish is actually a series of tiny holes acting as pressure sensors along the side of the fish.

They function by detecting changes in the water pressure around the fish and greatly supplement defects in the sensory organs such as poor iris functionality or non-chromatic vision.

Fish Sense

When something moves through the water (such as the insect larvae the wild betta loves so much) it generates a pressure wave.

The lateral line works to sense this change in water pressure and give a general sense of the location of the object with reference to the fish, much like echolocation in bats.

NOTES
All fish possess this important organ, and they’re typically visible as a solid or dotted line of small holes or sensitive cells from the gills to the beginning of the tail at the back of the fish.

Can Betta Fish Eat in the Dark?

Betta Side View
Betta Side View

Bettas are a diurnal fish species, meaning that they tend towards inactivity at night and have not adapted to seeing in the dark.

While betta fish see objects and can sense them with their lateral line, they will not be able to find food as easily. As such, we recommend only feeding your bettas with the lights on so that they can properly locate food.

TIP

When feeding your betta fish, a good rule of thumb is to take things slowly. If after 30 minutes there is still uneaten food in the fish tank, it should be removed to avoid the buildup of toxic ammonia as the food decays.

Feeding Betta Fish at Night

Additionally, assuming that your fish has become normalized to a proper day and night cycle it will not be as active in the dark.

They will be less likely to notice the presence of food and will not attempt to eat it if they are already in a resting state.

Trying to feed a betta fish at night is much like trying to get your kids to wake up in the middle of their slumber and eat a salad. Even if they are indeed hungry they’ll likely be too sleepy to care!

Betta Fish Day-Night Cycles

As with humans, betta fish need sleep to support their natural processes. They prefer eight to ten hours of sleep per night, giving them enough energy to be active, hunt for food, and swim during the day.

Along with keeping your fish awake for too long, having an excess amount of light can encourage harmful algae growth.

This can, over time, deplete the amount of oxygen in the tank and lead to breathing problems for the betta.

Natural Habitat

Given that in their natural habitat betta fish rely on the presence or absence of the sun to indicate when they should be sleeping or active, it’s up to the aquarist to generate this in the tank at home.

They need a calm, dark environment to fall asleep and plenty of light so that the betta fish can see and distinguish colors during the day.

NOTE
Using an aquarium timer on your lights can be a great way to keep a consistent schedule in your tank and avoid missing any critical light changes. A regular day and night is critical for a healthy happy betta fish.

Selecting Tank Mates

This means that when selecting tank mates for the betta fish, an additional challenge is in ensuring that they’re in the same aquarium as other diurnal fish.

Having too much activity going on in the tank while they’re trying to sleep means that the betta may get only a small percentage of the sleep that it requires to remain healthy and live a good life.

Are Betta Fish OK in the Dark?

Betta-Fish at the Corner of a Tank
Betta Fish at the Corner of a Tank

While sufficient light is key in making sure that betta fish have a proper day and night cycle, they do just fine in the dark.

The balance is in finding how much light they need throughout the day so that your fish sleep an adequate amount.

A relatively dark room can be a challenge for bettas, as they’ll have difficulty determining whether to rest or be active.

Providing Adequate Light

As such it’s a good idea to provide an adequate aquarium light to simulate a proper daytime for the fish so that they can be active, and turn this off when you want to create a sense of calm and rest.

Do Betta Fish Need A Night Light On At Night?

Betta fish do not need a night light at night.

Even if they wake up in the middle of the night, having a dark betta tank during the time that they should be sleeping will help them return to their restful state.

For more interesting info on how light affects beta check out this article

Are Betta Fish Scared of the Dark?

Of course not! For starters, betta fish don’t really feel fear much at all. Male betta fish in particular are known to be quite aggressive and hold elaborate defensive postures to keep away predators.

Even though they have poor vision and cannot see in the dark, this does not mean that they’ll be afraid.

Conclusion

Throughout today’s article we’ve discussed the question “can betta fish see in the dark?” The answer to this question is that yes betta fish can see in the dark, albeit poorly and with limited depth of vision.

It’s important that your betta fish sleep, and creating a dark betta tank at regular intervals is key to keeping them healthy in the long run so avoid always leaving the lights on and remember that they need the dark to stay healthy.

Feel Free To Share!

As always we hope that you’ve found this information helpful in solving your betta fish related questions.

Feel free to share this information with any other fish fanatics in your life, and we wish you the best of luck on your aquarium adventures!

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Mollie Newton
Mollie Newton
Founder of PetMeTwice. I love all types of animals from fish to fluff-balls! I also enjoy writing short stories and helping train animals 🤩