Can Fish See In The Dark?

Can fish see in the dark? Yes, the majority of fish can see in darkness because of evolved cone cells in fish eyes.

But, you should shut off the aquarium lights for a minimum of 12 hours to give the fish time to relax. Fish that live in the deep sea are able to travel in complete darkness.

The eyes of deep-sea fish are that are well-suited to dark conditions, but do all fish species see in darkness?

It’s not really “seeing” but they have organs that sense pressure which runs down the length of their bodies, known as the lateral line.

It lets them detect other animals based on the changes in pressure within the waters.

Electric eels and sharks also have special sense organs that permit them to sense the small electrical fields created by other animals.

Certain fish are able to see in the darkness better than others due to variations in the number of cones that are present in every species of fish.

Fish vision differs because the light is reflected differently in the water in contrast to the human eye.

The amount of night vision that fish have as well as the colors they see are heavily influenced by the depth in which fish reside. The idea of wavelength comes in useful in understanding the colors fish can detect.

For example, blue and green shades have longer wavelengths, so deep underwater fish appear blue or green to hide them from predators.

Are Fish Afraid Of The Dark?

Can fish see in the dark? This is a question that is asked frequently by a lot of us. According to science fish aren’t afraid of darkness.

Different species of fish require different habitats and conditions. Deep-sea fishing fish are in darkness for their entire life.

Aquarium fish are exposed to darkness and light. If the lights in the tank suddenly turn on following an extended period of darkness fish are frightened.

This is also true when you turn off your aquarium lights and you are left in complete darkness. This is due to the abrupt nature of the switch.

Dim lighting is ideal in the transition. Turning on the lights in the room or taking curtains off prior to plugging in the tank lights has proven to be successful.

So fish can get used to the dim light, and can then easily adjust to brighter lighting. This can be accomplished by turning off the lights.

Switch on the dim light and then after 30 minutes or more, you submit your fish to complete darkness.

Blue light can be beneficial during this transition. While blue light does not cause total darkness, it’s not optimal for fish to eat their food.

Thus, this light is best used to assist during the transition phase. Fish require 12 hours of light on average. It is crucial to have the day and night cycles for them as do humans and other living creatures.

They require 12 hours of dormant state to ensure they’re energetic the following day. If they don’t get those 12 hours, they will feel tired and lethargic.

Different species of fish have great vision in dark conditions and can detect movement with the aid of cone cells in fish eyes.

Did you be aware that fish can sleep with their eyes wide?

What Fish Can See In The Dark?

Researchers have discovered that fish that live in deep seas have a remarkable night vision that is better than the majority of creatures that are nocturnal.

Four species that have 5 or more genes capable of seeing clearly in the dark

  • Tube eye
  • Glacier lanternfish
  • Silver spinyfin
  • Longwing spinyfin

All four species live 1000-2000 meters below sea level.

They can also be able to see the green, blue-red, orange, and blue lights in the depths of the ocean. Amazing, right?

How Do Fish See Underwater In The Dark?

What do fish see in the darkness when they are blinded by light reaching the depths of an ocean is virtually zero? At night, there is complete darkness over the marine.

Fish are found deep underwater or near the ocean’s surface, It has been discovered that the latter tend to be able to perceive their surroundings, rather than be able to see them.

There are sensory organs in fish that run along their sides, which are known as lateral lines. These lines are all over the body and provide immense assistance in detecting creatures around it by gauging the changes in pressure in water.

They can detect movement in dim light conditions as well as in the dark. Certain fish species like electronic eels as well as sharks have the ability to detect movement through the electric fields generated by the animals.

Lateral lines aid fish not only in detecting movement but also aid them in navigating and moving through dark and muddy waters.

Aquarium fish are able to understand the position of each other through the lateral lines that detect changes in pressure and use sound waves in communication.

In low-light conditions in the dark, aquarium fish are able to detect fragments. They possess specific amounts of night vision that aid them in detecting the movements in their environment, but they mostly depend on their sensor organs.

Do All Fish Have Night Vision?

While fish do not possess eyelids, they have a layer of protection over their eyes that allows the fish to be able to perceive clearly in the water. Similar to humans they too have rods and cones that are present inside their retinas.

Similar to humans, sharks are able to perceive color. Since they have eyes on the two sides of their heads they have an eye-blind spot for each fish when they are swimming or eating.

Because of Rods as well as cones, all fishes possess a certain amount of night vision. Fish are able to see a portion of their surroundings thanks to cones found within their retina.

But, this is subject to the environment of the fish. Certain fish, such as walleyes, have excellent night vision, compared to other species of fish.

Fish that cannot see clearly move by using sensors.

As predators, they utilize their sense organs to detect the smell, see, and hear the sounds that their predators make. Night vision-seekers can survive in marine environments.

They can differentiate between predators and prey with greater efficiency. Humans have chemical components in their system, that is the reason we can see numerous shades.

The fish also have these chemical compounds. Fish also have the ability to detect UV spectrum.

How Do Fish Get Food Or Swim In Darkness?

Can fish see in the dark to get food? Fish can swim and hunt for food in darkness since they have sensory organs that are lateral and detect changes in pressure in the water.

This allows them to move forward and also show the direction they are heading. They are equipped with spherical lenses which provide them with superior peripheral vision to humans.

Sensory organs enable fish to sense vibrations around them. This tells them if something in their vicinity of them is moving or not.

Sensory inputs allow fish to recognize when the predator or prey is coming, without needing to be looking.

Certain nocturnal fish species, such as gobies and puffers, are very active in the evening and tend to eat food in complete darkness.

Fish can find food in darkness thanks to their sensory organs. The species of fish that are not night-vision impaired or lack clear night vision make use of their lateral sensor organs to move through the waters.

They can detect food items, and can even hear them. If food is thrown at them, there will be changes in pressure.

Sensory organs on the lateral side are able to detect this change and assess the substance that caused the change, before moving toward it.

The majority of aquarium fish don’t have night vision and prefer eating whenever there is light even in the dim.

They can detect vibrations in water via their special cells known as lateral lines, or neuromasts.

Certain fish species, like barracudina and angler fish, have specific adaptations to their bodies as they are found in extreme depths. These species depend upon their lateral lines as well as various sensory organs.

Sometimes, they can also produce lights of their own to offer help since sunlight does not penetrate into deep water.

Fish with large and round eyes can see more clearly in the dark than most species due to the reflected light of the moon as well as stars.

However, this is only feasible for species of fish that live near the sea’s surface. Aquarium fishes go into an inactive state when they are dark and can navigate toward the surface without colliding with each other while they sleep.

Do Fish Need Lights Off At Night?

As with all animals in the world, whether they are nocturnal or otherwise, aquarium fish adjust to illumination, followed by a time of darkness. It’s not recommended to leave the aquarium lights on during the night. and leave them on 24/7.

Not at all. Fish, as mentioned earlier, require 12 hours of rest which is most effective in darkness.

Whatever the space in which the fish are in, it is essential to ensure that the lights are turned off. The hours spent under lights can cause diverse types of fish to behave differently.

For example, fish that are nocturnal are known to hide in the rocks and are at a distance when it’s dark.

Different species of fish are, however, active, eat, move about, and interact with each other. If fish don’t get their required amount of sleep, they’re not very active.

The darkness is essential for fish to rest peacefully. Another reason to avoid having lights on all the time is the development of algae.

The green algae that grow on the glass as well as the light that is present in the tank will increase dramatically when lights are for a long duration.

If kept in the tank for too long, can reduce the supply of oxygen to aquarium fish, which can lead to the death of fish.

If the area in which tanks are kept naturally lit, you should cover the tank with a blanket or bedsheets to ensure the fish are provided with nights of darkness and rest.

Buy an on-off timer, and connect the light to it to set the timers to turn on and off to achieve the desired duration of daylight each day.


What Color Light Is Best For Fish?

FULL RGB SPECTRUM is good in all freshwater aquariums. Nothing brings out the vibrant colors and brightens your tank more than a complete and vibrant RGB (Red, Green, Blue) range of lights. It’s not just making your fish pop with color however, it doesn’t increase the growth of algae.

Is It OK for Fish To Be In The Dark?

Fish do not require lighting at night. The darkness of night is required for fish to rest. Additionally keeping the lights on all night can result in algae growing rapidly and overtaking your aquarium.

Can Fish Tank Fish See In The Dark?

A majority of fish are able to see in darkness because of evolved cone cells in fish eyes. But, you should shut off the light source in the aquarium for a minimum of 12 hours to give the fish the time to relax. Certain species of fish can see better in darkness than others due to the different numbers of cones that are present in each fish species.

Can Fish See Humans?

A tropical fish species is shown that can distinguish it from human faces. This was the very first time that fish have shown this capability. A tropical fish species has been proven to be able to differentiate from the human face.

Are LED Lights Good For Fish?

However, LED lights operate much more efficiently than standard fluorescents as well as metal Halides. They come with a variety of customizable lights with different intensities and colors. They can be used with aquariums that are planted or fish-only in the event that you select the ones with the correct output.

What Does Fish Do At Night?

Although fish do not rest like mammals do, the majority of fish rest. Studies have shown that fish lower their activity levels and metabolism but remain vigilant to threats. Some fish can float around and others wedge themselves into secure spots in the mud or coral and some may even find the perfect nest.

Can A Glofish See In The Dark?

GloFish (GlowFish) requires only a tiny amount of light in order to see under the water. You can see that the reflection of the light from GloFish is better in dim lighting settings.

Can Goldfish See In The Dark And Find Food?

Goldfish are not capable of seeing in darkness. They do have the ability to smell which helps to navigate through dark environments.
Like other fish, goldfish possess the Lateral Line System, which is a set sense organ. They are able to detect the changes in water pressure and guide them through the dark zones.

Can Koi Fish See In The Dark?

Koi fish aren’t very adept at identifying objects in the dark. There isn’t much requirement for Koi fish to see at night since they are unoccupied.
Koi fish tend to be most active in the daytime however, they do prefer to sleep in the evening when the skies remain dim and the temperature falls.

Can Molly Fish See In The Dark?

Mollies aren’t very adept at detecting darkness. Mollyfish utilize their line system lateral to assist in moving forward or being alerted in case any animal comes near them in the dark.

Can Guppy Fish See In The Dark?

No. Guppies can’t see at night when you turn off the light on their tanks.
Therefore, make sure to make sure that you have the lights on while feeding your fish. When the light is turned off the fish won’t be able to see anymore and will be unable to enjoy their meals.

Can Betta Fish See In The Dark?

Betta fish have poor vision in the dark. They are known for being found in water that is murky They prefer clear and fresh water. This is the reason they have less vision in the dark.
Bettas are particularly monocular. They can see objects from two directions simultaneously.


Can fish see in the dark? Fish have night vision, to a degree. However, rather than calling it “sight,” it is more appropriate to label this as sensing. A majority of fish are able to sense the smell and feel in darkness which aids them in their ability to move smoothly.

It’s like having a sharp night vision. Fish have sensitive senses that relieve the fish from any issues related to movement, even in the dark.

We at Fish Camp Rehab, have carefully crafted a myriad of interesting facts and fun for all to enjoy!


Dibyajyoti Bordoloi is the creator and author of, a third-generation experienced fish keeper and owner of a successful pet breeding farm. He is also a member of the Center for Wildlife Rehabilitation And Conservation (Assam), the Marine Aquarium Societies of North East India, and the Kaziranga Nature Conservancy of Assam.

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