Can Aquarium Fish See In The Dark | Lighting Tips

I remember walking through the aquarium as a small child fascinated by the sights. The different schools of fish, various sharks and touching the sting rays left a lifelong impression on me and others. Peering through the glass, observing the aqua life close up was nothing less than exhilarating.  After leaving the aquarium, thrilled by the experience, I was inspired to have my very own aquarium at home. However, one question has stuck with me since childhood. Can aquarium fish see in the dark? It may sound silly but even as an adult I found myself still wondering what the answer is.

I remember walking through the aquarium as a small child fascinated by the sights. The different schools of fish, various sharks and touching the sting rays left a lifelong impression on me and others. Peering through the glass, observing the aqua life close up was nothing less than exhilarating.  After leaving the aquarium, thrilled by the experience, I was inspired to have my very own aquarium at home. However, one question has stuck with me since childhood. Can aquarium fish see in the dark? It may sound silly but even as an adult I found myself still wondering what the answer is.

Can fish see in the dark?

With so many different species of fish, one cannot simply answer yes or no. In fact, it would scientifically inept to do so. There are freshwater fish who generally live near the surface and are exposed to sunlight as well as saltwater fish who live deep in the sea and are hardly exposed to any light. The truth of the matter is that different fish have different abilities to adjust to their surroundings. 

There are different ways for fish to navigate by sensing movement and or distance, other than just their eyes. For example, Goldfish have an excellent sense of smell which they can use to maneuver around at night. Whereas Guppies cannot see at night and actually need the tank light off at times for proper rest. Betta fish are known to have poor vision in the dark as well. Piranhas have great sight at night as they normally travel through murky waters.

On the other end of the spectrum, sea dwellers such as Dolphins use echolocation to navigate in dark waters in which they rarely have to rely on eyesight. Sharks are known for their keen eyesight and also hunt at night.

Simply put- some fish can see in the dark better than others. It will all depend on which type of fish you plan on bringing into your home. Researching the type of fish you want as a pet will be imperative.

Do aquarium fish need light to orient themselves?

Most aquatic fish can certainly use light to orient themselves. Being that they will be in a completely new environment with possible new fish neighbors, it is recommended to either have a light in place for the tank or get the fish acquainted with lots of natural sunlight. Moreover, depending on what type of light you use can affect the temperature of the aquarium tank. Certain fish cannot see without light at all. Taking all of this into consideration will make it better for the fish to get comfortable inside of their new home.

Can you leave your aquarium light on all night?

The answer to this question depends on your fish and if there is any plant life inside your tank. If you have any moss, coontail or weeds living in your tank then it is not recommended to leave your aquarium light on all night. Constant light may result in causing algae to grow wildly.  This effect can make the tank claustrophobic to your pet fish and create distress.

Additionally, certain fish need the lights off to properly rest. Alternating the aquarium light provides a balanced and healthy habitat for your fish which promotes longevity. Running your tank light in on a schedule can reduce your electric bill as well.

Should I leave lights on or off during vacation?

For those fortunate enough, a nice getaway is a great way for recharging your mental battery and taking a break from everyday life.  Unless you have nocturnal fish such as Common Molly or Cardinalfish, then you may want to have some light on while away on vacation.  When it comes to caring for your aquarium it is best to put your tank’s light on a timer if you are going to be absent for a long while. This will promote a balanced, healthy living space as mentioned before.

Long absences will also require someone to fill in for you and maintain the basic upkeep of the tank such as feeding, changing the water and possibly cleaning the tank.

What kind of light should I use in my tank?

By now you realize the importance of lighting inside of your tank. Not only will lighting mimic your pet fish’s natural environment, it will also allow you to see any health or maintenance issues that need to be addressed.  What is inside of your tank will determine what type of light you will need. For instance, having fish only, plants or reefs will need to be considered before you purchase your lights.

There are several types of lights you can use from LED, incandescent or fluorescent. LED lights are most common for fish tanks as they will not affect the temperature of the water.  However, some lights can dissipate heat, change colors and come equipped with a remote control.

There is not one right way to go about selecting your lights. It will truly depend on how your tank is designed and what is in your price range.

Once you’ve decided what type of fish you intend to make a home for, whether or not you will have plant life and or reefs, you can then choose the appropriate lighting system to accommodate them. Consider getting a lightning system that has a warranty. This will stretch your investment in the event the light isn’t as high a quality as you may have anticipated.

Will I need a timer for the lighting?

Unless you’re a homebody who works at home and rarely leaves, then it will be ideal to get a timer for your aquarium. There is a huge selection that you can find online and at your local pet store. This will make it easier for you to create a schedule for your fish to be with or without light. This is all part of building a comfortable habitat for your fish’s life which will hopefully promote a long and healthy life for your pets.

Be sure to always set your timer just in case an emergency happens and you’re unable to get to your home as you normally would. This will relieve your pet fish from unnecessary stress or an algae outbreak in the event that your schedule suddenly changes.

toxotes chatareus, archer fish in Thailand

Can aquarium fish recognize you?

You may not realize it but you can actually build a bond with your fish. Fish can recognize their owners. There are scientific studies that have revealed that fish can memorize their owners and show affection through jumping, swimming rapidly and flipping. Feel free to talk to your pet fish and even play with them.

However, experts have stated that tapping the tank too much can create a disturbance with your fish. Do not neglect your fish just because the live in water; rather, show them affection to promote good health and stability for them.

If you’re curious about owning an aquarium you may want to take the aforementioned information into consideration. The lighting in your tank is important so take caution when preparing a home for your fish. Researching the fish you want is imperative in order to make an educated decision on what water to use (salt or fresh), what food to use, which fish are compatible with each other and the best type of lighting. Fortunately, there is a good market for home aquariums, tanks, timers, LED lights and fish. That way you can gather all the essentials needed to successfully domesticate your new fish friends.

 Although my childhood question does not have a definitive answer, I certainly feel a lot more comfortable knowing how fish are responding in the dark. The different species of fish vary from one another as it relates to  size, eating habits and the amount of light required.

Bart Sprenkels

I have been keeping multiple aquariums since I was 18 years old. Just like many of you, I started with two goldfish but quickly learned they were not suitable for aquariums. Later, I switched to a tropical community tank and I also have two pet musk-turtles in a bigger aquarium. You can read more about me here.

Recent Content