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do fish need light?

Do Fish Need Light?

The maintenance of biological stability in an aquarium depends heavily on the light. Thus both its quality and quantity must be adequate. One famous common question is whether or not you should have a light for your fish.

Aquarium lighting is solely for our viewing pleasure; the fish receive no benefit from it. Plant matter in an aquarium needs light. However, if you choose to leave the lights on, ensure the fish experience at least 8 hours of darkness at night. The goal is to simulate the natural environment.

Stunning aquariums can be magnificent in-home attractions. The right lighting is essential for producing visually stunning aquatic scenery. Still, it’s important to understand that every aquarium has varied lighting requirements.

Do You Need To Have A Light For Your Fish?

fish in a lit fish tank
Lots of light in this tank.

I am sure you have noticed that whenever you see fish in a tank, there is always some kind of light source in there.

However, have you ever wondered, is that light for us to be able to see the fish for our enjoyment, or do fish really need light?

If you only have fish in your tank, you do not need any light for your fish. This is because many fish do not enjoy bright light. This makes sense as in their natural habitat in the ocean; it is pretty dark the deeper it goes down. In an aquarium, light is generally used for the following reasons:

  • So that we may see the fish at night; to enhance the beauty.
  • To ensure plants are still able to stay alive.
  • To ensure that the water’s temperature is maintained.

Fish do not receive a lot of sunlight. Light is therefore not advised unless you need it for one of the reasons mentioned above. In the wild, light only reaches a depth of 200 meters before it becomes completely dark. Additionally, scattered light in that depth is referred to as the twilight zone. Light is therefore not required.

The type of life you keep in the aquarium and your aesthetic preferences will determine whether you want it. For the first three months after the fish tank has been set up, the lighting should be turned on for around eight hours each day in a typical aquarium tank with an appropriate quantity of fish and plants.

It’s important to remember that even though fish don’t have eyelids and can’t close their eyes, they still need to sleep. Therefore, fish should have around eight hours of darkness per day, and it’s important not to turn on the lights too quickly as this could lead to a panic.

In What Instance Should You Have Light For Your Fish?

The live plants in your aquarium must have light. This is essential for the plants and not for the fish, as depending on the type of vegetation you have in your fish tank, the lighting needs to be strong to keep your plants alive.

Having certain light on top of the tank can scare, so to speak, certain fish. This may make them skittish, which will lead to them hiding. Simply put, fish do not need light even at night. Light is not crucial for fish-only tanks but is essential for tanks with plants, invertebrates, and corals.

java fern
Plants need light to help them grow.

How Much Light Is Good For Fish?

Around 23 ° of the equator, native tropical plants and fish endure 12 light hours and night each day. You should keep the aquarium light on for 12 hours a day to simulate tropical conditions. If tropical fish are present, provide them plenty of hiding places because some prefer low lighting.

In temperate regions where the length of the day varies with the season, minnows, goldfish, ricefish, and zebrafish can be found. Match the aquarium lights to the seasonal daytime to produce a more natural atmosphere.

For at least 8 hours, dim lighting with the correct spectrum is required if you’re keeping deep-dwelling species, such as rift lake fish. Certain spectrums emphasize the colors of fish. Ambient light need not be strong. The amount of light needed would be far greater if your setup included plants. But among the foliage, fish would find cover.

Don’t bother with lighting for the nocturnal fish. As far as possible, mimic the animal’s habits and natural environment. A few tropical fish are familiar with intense sunlight. However, many are found in muddy, discolored, black water or rivers in the jungle where sunlight is scattered. Do a search on the appropriate lighting needs. The goal is to imitate the day-night cycle.

Can Too Much Light Be Bad For Fish?

Fish have an internal day and night cycle, and therefore they require a dark period for them to not get stressed. If you have a light above the tank that you leave on the whole day, every day, it can be quite stressful to fish.

This is especially bad because stressed fish tend to have a weak immune system, making them even more susceptible to all kinds of sicknesses. Another reason why having the light on 24/7 for fish would be bad for them is algae.

Essentially if you have a lot of like plants in your aquarium, they will need light to thrive and live, and they play an essential role in sucking up the nitrogen in the water. Therefore if you have the tank lights on all the time, algae will explode in the aquarium because the plants will not be able to sufficiently suck up the nitrogen.

striped corydoras
Light helps us to see our fish better.


Having lights for a fish is not always necessary. Thus some people choose not to. Should you decide to have lights, just keep in mind not to leave the lights on all the time. In addition to stressing out the fish, especially those who depend on the day-night cycles to know when to sleep, this would also cause massive algae problems that are very difficult to eradicate.

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