betta-fish-see-dark

Can Betta Fish See in the Dark?

Much has been said about Bettas and the truth is we cannot get enough of this vibrant aquarium fish. From their dazzling beauty to bright colors and their territorial behavior to aggression, Betta Fish have always added liveliness to the aquarium.

Bettas are a common species of fish that have become popular in the aquarium business. They are part of the gourami family and have a reputation for being highly territorial. No wonder research studies have pointed out that male Betta fish are highly aggressive and are likely to kill each other if kept in the same tank.

Additionally, Betta fish are admired for their flowing fins and brilliant colors including other physical attributes. Because of their looks, Bettas have remained a preferred choice of aquarium fish among different hobbyists. But these fish are not easy to maintain, thus not a suitable choice for beginners.

For almost all species of fish, both in captivity or in the wild, vision is of paramount importance. This sense organ plays a crucial role in all animals, especially marine ones including fish. And this is where Bettas come in. Their eyes are more or less the same as those of terrestrial vertebrates, mammals, and birds in terms of their structure. The only structural difference is that  Betta Fish’s eyes have more rounded eyes as opposed to those of other animals.

Still on the structure, you will be amazed to realize that their retina have rods that allow them to have a monochrome vision as well as cones to facilitate color vision. This means that these fish can see and distinguish colors. Interestingly, some fish can see polarized or ultraviolet light.

So, the question is, can Bettas see in the dark? Generally, their vision is a little bit weak while in the darkness. As a matter of fact, their vision is relatively poor due to the slow iris functionality. Consequently, these fish find it difficult to adjust swiftly to different degree of brightness.  To overcome this weakness, Bettas use the lateral lines that run down their bodies to help them swim around where there’s insufficient light or no light at all.

Read on and find the most appropriate answers that address the question deeply and in details regarding the eyesight of this fish and the best ways of taking care of them. Before we get down to the subject matter, let’s learn a great deal of the day and night lifecycle for Bettas.

Betta Fish Day-Night Lifecycle

Betta fish are active across the day because there’s plenty of light. During the day they can easily eat their food and find their way around the aquarium.  At night, these fish take a rest by sleeping because there is no light. Sleeping is essential in helping them relax while restoring lost energy during the day.

You should never keep your Betta fish in a relatively dark place for a period exceeding eight or ten hours. These species of fish need a minimum of ten hours of light per day. The light helps in upkeeping their bodily mechanisms and natural processes. As such, it is advisable to provide their aquarium with enough light for their well-being.

There’s a theory stating that Bettas require enough light in the darkness. Absence of light is likely to make them inactive. On the contrary, some experts say that there is no known risk of keeping your fish in the darkness. Their argument further states that when the fish are in the darkness they will remain as active and healthy as they would be when subjected to a sufficient amount of light.

Betta Fish Have a Weaker Vision in the Darkness

As stated earlier, Bettas have a slightly weak vision especially when they are subjected to darkness. Even though these fish grow in relatively murky waters, they enjoy staying in clean fresh water. That is why their vision is weaker in the darkness compared to when there’s light.

Betta fish are known to be monocular. This means that they are capable of seeing objects in two different ways or directions simultaneously. On the other hand, these tropical fish lack in-depth perception as far as their vision entails.

Bettas experience relatively poor vision due to slow iris functionality. This problem makes it difficult to adjust quickly to changes in light intensity. Luckily, there’s a way out of these difficulties. Betta fish can use their lateral lines to aid them in finding their way in the darkness. Their lateral lines have tiny holes that help them in determining water pressure around them. The differences in pressure enable them to approach objects when it is dark.

The Chromatic Vision of Betta Fish

According to researchers, the diurnal animal retina comprises a large number of rods and cones. These two features play a significant role in animals, particularly the fish by enabling them to distinguish different colors when there is light.

However, the situation is different in nocturnal animals. Here, the cones are more than the rods in number, thus allowing nocturnal animals to see clearly in the darkness better than diurnal animals although they perceive fewer colors. For that reason, you can confidently say that fish are not able to see all colors although they are capable of seeing different ranges of colors.

The chromatic vision in fish depends solely on turbulence or depth of water around them. The visions may turn out to be monochromatic, dichromatic (for those fish in turbid waters) trichromatic (for those fish found in coral or reefs) and tetrachromatic (for most of the fish found in crystalline seawater).

It is evident that Bettas can see a wide range of colors although it is not yet clear if they can see all colors. This is due to the fact that Bettas are diurnal fish, thriving in the clear freshwater or stagnant water. In this case, Betta fish will need some special assistance to see better and identify objects in the darkness.

How Betta Fish See Images?

Cones enable Betta fish to see images in what is called high spatial and temporal resolutions. These fish see the light of various wavelengths thus providing them with the color vision for different objects around them.

The ratio of cones to rods depends largely in the ecology of each type of fish. For instance, those that are active across the day have more cones compared to those that stay active during the night. The use of color vision is prevalent in fish especially in those environments with full light spectra. For example, your Betta fish will find it easier to use its color vision ability at the surface rather than at the bottom of the tank where there is poor spectral composition.

Apart from that, you need to know that photoreceptors on the Betta fish retina is not distributed uniformly. As a result, you will discover that your fish has two or three sections on its retina that is specialized in achieving high sharpness. This is important when it comes to catching their prey in water.

There are also some variations in the distribution of photoreceptors throughout the whole life of your Betta fish. This phenomenon is common when your Betta fish shifts from one habitat to another in the course of its lifecycle. In most cases, the light goes through the retina but only a small percentage causes some reactions to the sensitive cells.

The Lateral Line on Betta Fish

The lateral line is a series of pressure sensors that are concentrated along the body length of your Betta fish. These lines are a little bit shadier than the rest of the body and are a set of small pits made up of delicately pressure-sensitive or tuned motion cells. These cells detect any minor changes in water pressure around the fish. Therefore, the lateral line helps your Betta fish to be aware of what is happening in its immediate environment. Your fish can use this line to find food without necessarily depending on their vision or upon sensing the danger in their territories and take cover to avoid getting killed.

Given that Bettas don’t have eyelids, it is obvious their eyes will stay open even in the darkness. This gives you a valid reason to believe that your Betta fish can see when it’s dark despite their poor vision. To prove this theory, you should turn out the lights in your tank and observe how your Bettas behave. Certainly, you will see them panicking as a sign of being terrified. This is a clear indication that they can see in the absence of light.

Final Thought

Better fish are diurnal animals whereby they stay active in the day and take a rest during the night. In other words, they prefer light to darkness because they have a poor vision that cannot allow them to see objects clearly in the dark. This statement doesn’t mean that they cannot see anything in the absence of light regardless of their poor vision. So, Bettas can indeed see in the dark but not in the same way as they do when there’s light.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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