Can Goldfish See In The Dark?- Some Goldfish Facts!

Can goldfish see in the dark

Do you have those glittery goldfishes in your aquarium? Well, then you must be one of those who look at them in the night and wonder can goldfish see in the dark? It is probably the most famous query of all those aquarists who pet a goldfish. 

But do you know what the fun fact is? It’s not just your neighbors who have their eyes on you; also, the goldfish in your tank has much superior eyesight on you. Vision is something that is quite a highly developed sense of goldfishes. 

So, do you want to know more about the vision of your pretty little goldies? Well, keep reading this article on “can goldfish see in the dark,” you’ll get all your answers.

Can Goldfish Live in the Dark?

As you are interested in knowing, can goldfish see in the dark, then it’s evident that you wonder whether they can also live in the dark? Well, the answer to this question is pretty mixed. If you think of petting goldfish, you need to balance both the light and dark atmosphere in your tank set-up.

An aquarium containing goldfishes requires light, but, at the same time, darkness is of much importance for their survival. Yes, they can live in the dark! Instead, darkness is quite essential for their health and growth as you and me. Darkness helps them to have a quick nap, just like us; impressive.

Goldfishes don’t have eyelids; changes in the lighting conditions are signs for them, when to sleep and when to swim.

However, even if they can live well in the darkness, staying in there for a long time can make them fall ill easily.

Can Goldfish See in the Dark?

There is no doubt that a goldfish’s senses are well-developed, and they are sensitive enough with their vision. However, the answer to the question, “can goldfish see in the dark,” the answer is, unfortunately, NO! 

These pretty golden-colored fishes use their sharp senses in the dark to hover around in the tank, but they cannot see anything.

What Happens When a Goldfish is Left in a Dark Place?

As goldfishes survive smartly in dark scenarios in their natural habitat, it will not impose a problem for them when you put them in a dark place. But they require an optimum amount of light to maintain their normal life cycle. 

Just the way we wake up in the morning and stay active in the daylight, goldfish also remain energetic in the light and heat during the day time to perform all their daily activities. They move around in the water and keep eating. Whereas they usually take a nap at night when it is dark. 

So, if you are planning to keep them in the dark to test if goldfishes can see in the dark, make sure you are not keeping them for more than 12 hours. Staying for long hours in the dark can create many illnesses as it does in humans.

Can Goldfish See Food in the Dark?

Most of the goldfish owners ask this question, Can goldfish see in the dark when I serve them the food? These gold glitters use their primary vision and lateral line organs to find food in the night. Their specialized vision allows them to see tetrachromat colors, making them find food of all colors, even in the dark.

However, do you know another interesting fact about goldfish’s vision? These fishes can absorb UV light to see in the dark, unlike humans. This ultraviolet vision makes it easier for the goldfishes to spot any water movement in low light or dark situations. 

So now, are you going to inspect your goldie to find out if goldfish can see in the dark?

Can Goldfish Eat in the Dark?

Can goldfish see in the dark is not the only exciting thing to know about these colorful aquatic species. So, do you want to know a more interesting fact about them? Goldfishes use their strong-smelling sense when there is something yummy to eat nearby. Well, this is something crazy about them. 

Goldfishes have a nose, which does not have any connection with their mouth or respiratory system. They merely own two blind pits, along with their strong-smelling receptors. Whenever water flows through these pits, the receptors’ information is conveyed to their brain cells, which makes it easier for them to sense food in the dark. 

So, have you missed feeding your pets in the day time? Don’t worry; your hungry little goldies will wait for you and stay awake to get fed even in the dark.

How Do Goldfish Swim in the Dark?

Well, when it is dark, the goldfishes do not swim properly in the water. As the dark time is ideal for them to sleep, they stay near the ground level and slowly hover about. 

Do you know they also tend to use their other lateral organs and the smelling sense to know if anything is approaching them in the dark? What a developed sense these little ones have, isn’t it?

What Happens When Your Goldfish Gets Too Much Light?

Too much light is not necessarily harmful to your goldfish, just like too much darkness. But it can harm the fish if exposed for a long time. Offering too much light for a prolonged period makes it difficult for them to regulate their daily natural lifestyle. 

It can also harm the chemistry of the tank water turning foul. So, are you going to keep your goldie under too much light, even after knowing this?

Is Direct Sunlight Bad for a Goldfish?

why is my goldfish turning white

The answer to your querycan goldfish see in the dark, is not the only thing you need to know about your pet. You would want to well-acquainted with every fact while keeping a goldfish in your aquarium. 

Direct sunlight is not going to harm your goldfishes right away. But keeping the tank in sunlight will increase the water temperature, which, in turn, will make the water a poor living condition for a goldfish. Why? Well, that’s because direct sunlight reduces the dissolved oxygen level in the tank water drastically, making it difficult for the goldfishes to breathe. It can even lead to goldfish drowning/suffocate to death.

Do Goldfish Tanks Need Aquarium Lights?

Like darkness, light is also a must-have component for ensuring your goldfish’s proper living condition in the tank. The appropriateness of light helps the goldfish to perform the usual biological process of healthy living. 

For a goldfish tank, fluorescent lighting serves best because it does not heat the water much and also makes the tank condition healthy for their growth.

Can Goldfishes See Outside the Tank? 

Now your queries about goldfishes can shift from “can goldfish see in the dark” to “can they see outside the tank.” Well, the answer is going to satisfy you. Because yes, they can see through the glass, and they have pretty clear eyesight. 

Do you know these aqua species can even see more shades of colors than humans? Goldfishes are very good at tracking objects, which are fast in motion. 

However, it is quite normal for most of the fishes that their vision lacks proper depth. When the distance gradually increases, the goldies start to see everything with a blurry picture after a certain distance. Well, there are many more exciting secrets to know about your goldies apart from “can goldfish see in the dark.”

Can Your Goldfish See You?

You must be wondering if your goldfish can see you or not. So, let us give you some more interesting facts about your golden aquarium buddies. Do you know what the Oxford University scientists told about goldfishes? 

The goldies have many hidden depths in their vision. Your goldfish can see you clearly when you are near the tank, as they have a bright vision. But do you know what is even more bizarre and exciting? Your goldies can see you and are capable of recognizing you and remembering you; this means your pet can recognize you surely from the others.

According to Oxford University studies, goldfishes can easily pick up your face amongst 44 different varieties of human faces. So, doesn’t this capability of your goldie make you feel happy and proud? We are sure it does!

Can Your Goldfish Hear You?

Besides your query “can goldfish see in the dark,” another thing that you might ponder over about your goldies is whether they can hear you or not. 

According to BMC Neuroscience, Bio-medical central, goldfish range of hearing sensitivity and bandwidth is from 20 to greater than 4000 Hz, with the greatest sensitivity between 400 and 1000 Hz. Whereas the human voice frequency range from 165 to 255 Hz for an adult woman, while for a man, the frequency range is 85 to 155 Hz.

The fish do not ear like you and me; they have an inner ear located inside the fish’s head. The inner ear that contains small bone structures responds to the sound waves. From the fish head to tail, run lateral lines which detect vibration in the water molecules; when the sound wave passes through the water molecules allows the fish to hear the sound and its direction.

You can tap on the fish tank or make your goldies aware with little sounds that you are here. However, they are not going to respond proactively. You can easily talk to them, though not sure whether they will be able to listen to you or not. Nevertheless, also feel free to share all your secrets with them; they will not tell anyone!

Do Goldfishes Sleep?

goldfish sleeping

Why not? Just like most of the other species, goldfish sleep as well. And you know what is even more fascinating? They take a nap in the nighttime just like us. So, while going off to sleep, you don’t have to wonder what your goldies do in the tank. Just tell them goodnight with a flying kiss, as both you and your goldfishes are going to have a nice sleep when the lights are off!

It is not necessarily the night hours, which is considered the nap time for goldfishes. They have a good sleep whenever they sense a quiet and dark ambiance. 

But do you know you can even train your lovely goldies to follow a particular sleep schedule? Yes, you heard that right! By adjusting the light in the aquarium, you can easily teach your goldfishes to go off to sleep only at night. Such obedient fellows, aren’t they?

How to Tell if Your Goldfish is Sleeping?

Now that we know the Goldfish sleep to rejuvenate, the emergence of questions like where they sleep, how they sleep, etc., is pretty apparent! Well, you can’t expect the little goldfishes to lie down while sleeping, just like us, isn’t it? 

But there are specific changes in their motions, which will make it easier for you to spot whether they are sleeping or not. So, are you wondering how to spot those changes? 

Well, when a goldfish is sleeping, they become barely active. These fishes tend to stay in one place and try to maintain stability in their motion. They seem to hover around in the tank at a lower water level, at just a one-inch (2.5 – 3 cms) from the bottom. At the same time, their head keeps going downward slightly.

Is it still difficult for you to discern? Then you can try focusing on their way of changing colors while they are asleep. If you notice, minutely, you will see that their color fades out while they are in sleep. Don’t get frightened; your stunning goldfishes will come back to their natural shade when they are awake. 

But do you want to know why they change their colors while sleeping? Well, it is a pretty smart trick of self-defense for them. They do it to protect themselves from predators.

Do you want to know another fun fact about goldfishes? Their deep sleep is not that deep in real. Their brainwaves remain the same, even when they are asleep. Hence, this attribute keeps them conscious of their surroundings and saves them from predators if they attack.


How to Maintain a Healthy Goldfish Tank?

goldfish tank

Now that you have got your answer to the question, “can goldfish see in the dark,”; planning on keeping some goldfishes in your tank? The first thing you would want to know is how to take care of goldfish and maintain a proper aquarium to create a healthy environment. 

Here’s all you need to know for maintaining a healthy goldfish tank.

Tank Size

The tank size that you will pick for your goldie will play a vital role in their living. The size of the aquarium decides the proper growth of the goldfish. 

If you are thinking of a bowl or a small tank, then it’s a big NO! Maintain the thumb’s rule of a 20-gallon tank per goldfish for their healthy growth.

Water Parameters

Water parameters are the next thing on which you would want to keep your particular focus. Generally, goldfish’s water parameters are a temperature range of 68 – 75°F (20 – 25°C), acidity 6.8 to 7.6 pH with a water hardness less than 12dGH, and carbonates and bi-carbonates 80 to 180 parts per million. Regular testing of all the water parameters with a test kit is a prerequisite in maintaining any aquarium tank.


Also, don’t forget to ensure a proper filtration system as goldfish produce a massive bio-load. The filter is not just filtering the particle, debris, etc., in the water. The aquarium filter houses beneficial bacterias/enzymes that are necessary to process ammonia and nitrite to nitrate. This process is called the nitrogen cycle. Remember to opt for a canister filter!

Goldfish Diet

Always give your pets a proper diet to make their tummy happy and healthy. Goldfishes are omnivorous, opportunistic eaters. So you can easily feed them with both veg and non-veg food items. Give them veggies and fruits like broccoli, spinach, peas, apple, and orange in a finely chopped form. Remember to blanch the vegs before feeding your goldfish.

Feel free to feed them with high-quality commercial pellets, flakes, and brine shrimps & bloodworms as an occasional treat. But make sure you do not give them loaves of bread. 

Now, are you thinking about how many times you should feed your little pet? Well, we recommend you to feed goldfishes 2-3 small meals a day to ensure their healthy growth and development. 

The thumb rule is to feed only as much as they can in 3 minutes. Left-over food is the topmost culprit for ammonia poisoning of your goldfish. Ammonia poisoning or ammonia spike is the top reason why your goldfish turns white suddenly and dies or why your goldfish turn black apart from genetics, which is harmless.

Signs of Low Oxygen

Oxygen is a crucial parameter to check on in a goldfish tank. 

But how to detect a low oxygen level in the tank? Well, here are the signs that can help you identify low dissolved oxygen levels.

  •  Lethargical behavior of your goldfish
  •  A tendency to come onto the water surface gasping for air
  •  Eating lesser than usual or not eating at all.
  • The rapid movement of their gills and difficulty in breathing

What are the Causes of Low Oxygen Level?

Well, do you know what causes the lowering of oxygen level in the tank water? Here are your answers.

  •  The elevated temperature of the water 
  •  Overstocking of fishes
  •  Use of chemical medication in the water 
  • Off pH balance
  • Decomposed plants
  • Leftovers
  • Overfertilization/excess nutrition and excess algae
  • Insufficient lighting arrangement for live plants

How to Optimize the Oxygen Level in a Goldfish Tank?

If the oxygen level in your tank water has gone low, don’t worry, you can quickly bring it back to the optimum level. Wondering how? Check out the ways given below. 

  • Adjust the water temperature
  • Complete Water Change
  • Adjust the pH of the water by regularly topping of water.
  • Use a de-chlorinator to clean the water before adding it to the tank.
  • Give proper lighting to the live plants to make them produce more oxygen 
  • Opt for a battery-powered air pump or air-stone to deliver stable oxygen in the tank water
  • Optimize the filtration to maintain optimum dissolved oxygen level in the water

Can Goldfish see in the dark?-Wrap-up.

So, what is the first thing that you are going to do after reading this article? Wait, let us guess. You are going to test if your Goldfish can see in the dark, right? 

Well, that’s a pretty good experiment to start with. But make sure you are not disturbing your little pets too much to track their activities in the dark. Just sit peacefully and watch calmly whether a goldfish can see in the dark or not.

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