Do LED Lights Hurt Fish Eyes?

Many aquarium owners wish to highlight their waterscape and show off their fish. One way to do this is through introducing lights. While many tanks come with overhead lights, these don’t offer a unique look to your tank or your fish.

Nowadays, more LED lights come on the market, yet they can still be relatively new for something specific such as aquariums. It leads many aquarium owners to ask the question.

Do LED lights hurt fish eyes? Fish are not as reliant on light as your underwater plants. Thus, LEDs won’t affect the eyes of your fish. However, there are things to know about lighting and if LEDs may affect other parts of your aquarium.

Do Fish Like LEDs?

Fish can’t tell the difference between one light and the next. They can, however, detect the brightness and heat emitted by any lighting system.

Excessively bright lights can be harmful to some fish. Therefore, if your fish freeze in fear or and hide when your lights are on, it’s possible your lighting is too bright.

Things should be better for the fish if your LEDs are too bright and you have a chance to adjust them. Another thing you can do to help is possibly adding extra plants to your tank to offer to shield against the lights and allow your fish to swim freely.

Why Use LEDs for Aquariums?

Because of the scarcity of LEDs, you may wonder why to bother. We already know they don’t hurt fish eyes unless the brightness is ramped up, so there has to be another reason they are worth the investment.

The best lighting options for freshwater tanks are standard fluorescent bulbs, compact fluorescent bulbs, metal halide lights, and LED lights.

The recommendation is to avoid incandescent bulbs since they are only suitable for small aquariums and delivering too much heat.

Regular fluorescent lights supply good light intensity without too much heat. Compact fluorescent bulbs offer more light, yet they are smaller and are often the type you find in your aquarium hood.

Metal halide lights offer the advantage of being full spectrum to reproduce the natural tropical lighting freshwater fish will have had in their native environment.

Besides this, full-spectrum is perfect for optimal growth and photosynthesis in your aquarium plants. Downsides here are the large amounts of heat they emit.

How Much Light Will My Fish Need?

Your primary aim as an aquarium owner is to mimic the amount of light your fish receive should they be in their natural habitat. Some natural light will enter your aquarium since the location will be lit from the sun or either by the sun outside or by the house’s lights.

You should aim for 8 to 12 hours of sleep per day for your fish, regardless of the bulb type. Many tank owners use a timer to make sure their aquarium lighting rigs come on and turn off at the same times each day.  

Pros and Cons of LEDs for Fish?

If you are considering LED lighting, there are a few things to consider. Here are the advantages and disadvantages of using LEDs in your aquarium.


Energy Consumption

Running LEDs requires less energy than conventional bulbs. They are energy-efficient and consume up to 80% less power than your regular aquarium lighting. Such is the reduction; you can get your return-on-investment back within the first 18 months.

Low Heat & Lifespan

Because LED lights do not produce the same amount of heat as fluorescent light bulbs, they will not heat your aquarium water. However, they still need proper air circulation to make sure any heat they emit doesn’t shorten the LED’s lifespan.

LED lighting, by default, will outlast any other type of bulb, and you can find the controller needs replacing before any of the LED lights do.

Light Intensity

You can dim LED lights and program them to replicate dimming at sunset and sunrise. This is beneficial when you have nocturnal fish in your tank, as dim blue light can remain on to simulate moonlight.

Depending on your LED lighting system, you can have this adjust itself for plant growth.

LED Lighting Colors

Led bulbs are available in many colors and can add interest to your aquarium. You’ll find them sold by spectrum and most often in Kelvin or K units. While you may think these are just different colors or brightness, you’ll find they have a much greater impact on your fish. 

For instance, an LED that offers an 8,000K white spectrum will enhance colors of red, orange, and yellow fish. Besides, you’ll find your plants can also benefit as it increases photosynthesis.

If you wish to enhance your greens, blues, and reds, you can do so using a magenta or magenta/blue LED, which will also offer your plants additional support.

You can mix these with the 12K white, which delivers all you need for a planted aquarium. If you wish to replicate a lunar effect, you can use the 445-nanometer royal blue lights, which are very popular.

Should you have or wish to purchase any fluorescent fish, these are the lights that will make them stand out and glow vividly.

Light Coverage

You can buy custom lighting fixtures and controllers, or you can purchase LEDs in strip form. These allow you to tailor your lights to your aquarium setup if there isn’t a readymade system available.

LED light strips are affordable and allow you to cover the length of your tank quickly.


Anything that has an advantage will have a disadvantage somewhere. There aren’t many with LEDs, yet there are some.


When you decide to purchase LEDs, you’ll find them more expensive than conventional lighting systems. However, even though your upfront costs are higher, the longer you use these LEDs, the more you recoup and save money.


LED lights are not included in many aquarium kits that include a light or a hood with light. You still only find standard fluorescent light bulbs available in popular kits or combination units. It’s possible to retrofit your hoods with LED options, or you go for the DIY option and make your own.

Similarly, most light fixtures are still only available with fluorescent bulbs, so there isn’t a wide selection to choose from.

Underwater Plants

Another area where LEDs fall short is in the realm of planted aquariums. Many LED light fixtures are only suitable for low to medium levels of illumination.

In most cases, this will suffice for most fish and certain plants. When you get to other plants and larger tanks, Kelvin ratings of 6500K to 7000K make more sense. When you have plants requiring lots of light, you may need to search for a more powerful LED lighting option to cater to the plant’s needs.


LEDs are the future of lighting, and it is good to know they won’t harm the eyes of your fish should you decide to use them.

The biggest concerns are finding the ones you wish to use and making sure they offer your plants full spectrum capability.

LEDs offer a lot to any aquarium, and the more significant expense can easily be justified by longevity alone. Since there is very minimal heat output, and you can pick different colors for your use.

No tank owner should consider conventional lighting systems over choosing the safer option of LEDs for their fish.