Can Goldfish See In The Dark? The Shocking Answer

Goldfish are beautiful, and you’ve probably heard that they’re very intelligent fish. But now you might want to know some fun facts about this fish. Can goldfish see in the dark?  Can goldfish see colors? What happens when you put a goldfish in a dark room? Can goldfish see outside the tank? All these questions will be tackled in this article and the answers may take you aback!

Can Goldfish See In The Dark?

By observing how items absorb, reflect, or transfer color, goldfish can sense color and recognize objects in their environment. Goldfish have color detectors in their retina at the rear of their eyes, which allows them to see in color. The cones of goldfish allow them to see in color based on a precise mix of primary hues.

Shades of red, blue, and yellow may be seen by human eyes. Goldfish, unlike humans, can perceive ultra-violet and infrared light, making them sensitive to polarized illumination at twilight and sunrise. Goldfish can sense reflected light off nearby fish’s scales, which helps them locate each other and spot prospective prey or predators while avoiding undesired reflections beneath the water. Goldfish can perceive a variety of colors, including red, green, blue, and ultraviolet light, thanks to their sophisticated eyesight.

So can goldfish see in the dark? As said above, goldfish have excellent vision, but they are unable to see in the dark. Alternatively, they swim about the tank at night using their acute sense of smell. They also have a lateral line system that aids them in detecting any vibrations or movements in the surrounding water.

Can Goldfish See In The Dark? The Shocking Answer

What Happens When You Put Goldfish In A Dark Room?

Goldfish do not have eyelids, so they won’t be able to sleep if they close their eyes. Goldfish need 8 to 12 hours of complete darkness to survive. Your goldfish will get a light and dark cycle if you use a light period plan for manual lighting and a timer for automated lighting. When the light starts to fade, goldfish, like humans, begin to detect brightness.

The goldfish will stop moving once the surroundings become dark, and this is how they relax. It’s natural for their eyes to dart about and look at you; this helps them keep an eye out for predators. Pond goldfish that are exposed to natural light and darkness have stronger eyesight than goldfish that are exposed to artificial light for extended periods of time. Despite their weak eyesight in the dark, they utilize their lateral line and scent to grasp what is going on in the aquarium while they sleep.

Therefore, in order for your goldfish to sleep, aquariums that come with either bright or low-tech lighting must be adjusted depending on what kind of your tank set-up. For instance, 12-hour high-intensity lights (like those used by professionals) are brighter than standard fluorescent bulbs; meanwhile, dawn simulators give off only a gentle glow perfect if the owner wants softer tones while still getting enough illumination needed by any type of species.

How Do Goldfish Sleep? You May Be Surprised

When it’s dark and calm, goldfish snooze. They enjoy napping in the afternoon, but most don’t go back to sleep until the evening since they have eyelids that keep their eyes open when sleeping, unlike humans who blink every second!

With their heads slightly bent downward, goldfish float about 1 inch over the bottom of their tank, allowing them to breathe easily without colliding with any obstructions in front or behind them. Aquarium fans may observe that lazy goldfish will sleep almost anywhere–even upside down if necessary (though chances are, you won’t see this).

Make sure your goldfish is in the dark if you want them to sleep well. It’s also crucial that there’s no sound source near their aquarium, and that it’s turned off for 12 hours at most!

You can watch the video about a goldfish sleeping below:

Do Goldfish See Color Outside Of The Tank?

Yes! Goldfish are able to look beyond their tank and detect distinct colors. Your goldfish can see you if you’re wearing a red shirt. Beyond the aquarium walls, the glass distorts the colors and forms. If the tank water contains tannins or algae diatoms, the colors may seem dull through the glass.

It’s worth mentioning, though, that while goldfish may live contentedly in the dark, if they spend too much time there, they can eventually grow unwell. Goldfish are nocturnal and sleep throughout the night, but that doesn’t mean they don’t need to be active at night!

Goldfish are known for their ability to not only navigate in complete darkness (even when blindfolded), but also to use it as a shelter from predators or to find food by feeling around with their barbels, which are fin-like feelers on each side of their mouth that help them detect things bumping into one another underwater.

Though they may not be adept at seeing far distant items, up close, goldie is ideal since most things beyond 10 feet would blur owing to human limitations known as depth perception. Their eye positioning prevents them from seeing anything except when staring into the water, which has the advantage of making everything around them appear crisper than when humans see distant objects via air bubbles, etc.

You may also like: Can Goldfish Live in a Bowl? Myths Debunked

Can Goldfish Talk And Grow?

Goldfish have the excellent hearing ability. They can hear both low- and high-frequency noises, but they don’t generate any noise or sound of their own; instead, their body language does!

Goldfish are commonly marketed in a bag or bowl, although they may reach a length of 12-14 inches. The longest Goldie, measuring roughly 18.7 inches, was discovered in the Netherlands!

Some individuals take meticulous care of their goldfish pets; one man even purchased a fish that had been surviving for 15 years after its previous owner had given up because he couldn’t afford it. However, most don’t survive much more than ten years on average since it all relies on how much food you feed them as well as the quality of the water you provide.

Can Goldfish See In The Dark? The Shocking Answer

How To Create A Healthy Environment For Goldfish?


Because goldfish are cold-water fish, you should keep the water temperature in your Goldfish tank as low as possible. A goldfish’s optimal temperature is from 65 to 75 degrees Fahrenheit; excessive temperatures might result in lasting nerve damage and even death!

People keep their tanks at proper levels in a variety of methods, but one of the simplest is to place an aquarium fan near them, which cools the air surrounding it as well–the flow from these devices can assist minimize heat stress on both sides of the equation (your plant/invertebrate buddies inside!).


Goldfish should be fed twice or three times every day. You have two options for feeding your goldfish: vegetarian and non-vegetarian meals.

For their vegetarian diet, you should feed them veggies like peas, spinach, and broccoli, but meatier alternatives like apples and oranges can suffice in place of this fruit’s absence from the list if given sufficient quantities throughout its life.

Tank Size

Goldfish can be kept in a tank as small as 10 gallons, but it will grow poorly and become stunted. The best size for the Goldfish’s Tank is 20 gallons – that should keep them happy!


Can Goldfish See In The Dark? The Shocking Answer

It’s critical to keep the optimum quantity of dissolved oxygen in your fish tank for healthy development. Goldfish and other types of aquarium fish should have a PPM of 5 or greater, according to the FWS (this varies depending on species).

When there isn’t enough oxygen in a Goldfish’s tank, it can cause a variety of issues. For one thing, your fish will repeatedly come to the surface and gulp for breath, a condition known as “prolonged exposure.” He may become less energetic or have hard breathing due to a shortage of oxygen (more info). Finally, if you detect quick movement in their gills, it means they’re not getting enough of this vital gas!

Pour some water from an elevated height if you have a low-oxygen problem and are looking for strategies to boost the quantity of oxygen in your aquarium. If required, major water changes (about 50%) can be done, however, it’s preferable to start with fresh new water before adding any additional additions like plants or substrate, since these may create problems when combined together!

If it isn’t possible, use one of these battery-operated pumps instead during power outages; simply put one into one outlet while another is cycled on low every three hours near sources like HOB filters.

In A Nutshell

We hope that this post has provided you with answers to your question “Can Goldfish See In The Dark?” Many people are unaware that goldfish can see color, much less perceive more colors than humans. Keep artificial lights on a low level and make sure you don’t have any moonlight-mimicking lights on at night to make it easy on your goldfish’s eyes. Along with their stunning colors and personality, goldfish are magnificent, and now you know they can see in color as well!

Related articles: 

Do Goldfish Sleep? When, How Long & How to Know

Do Goldfish Lay Eggs? What They Look Like?

Do Goldfish Get Lonely Living Alone?

You can also visit our Tropical fish section to read comprehensive guidance on taking care of popular freshwater fish such as plecos, tetras, and gouramis. Also, you can get some useful tips on creating a healthy fish tank community and much more!

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