Are LED Lights Harmful To Fish? {Pros & Cons of LED Lights}

Are you looking to add LED lights to your fish tank but are thinking are LED lights harmful to fish?

Will it hurt their eyesight or cause stress?

In this article, we’ll discuss if LED lights are harmful to fish.

Are LED Lights Harmful To Fish?

No. As long as you monitor and adjust the intensity of LED lighting in your tank without keeping them on longer than 12-14 hours a day

The fish will not be harmed. LED lights have taken over the fish keeping hobby and studies have proven their safety.

Will LED Lights Hurt Fish Eyes?

Aquarists wish to show off their beautiful tanks, fish, invertebrates, plants and decorations with LED lights. The options of colors, placement or designs seem to be endless nowadays.

LED lights are getting cheaper and more specific for every hobbyist’s tank needs. Your fish are actually not as reliant on the lights as much as your aquarium plants. LED lights are deemed safe for the eyes of your fish.

We can look further into other factors, but rest assured that common LED lighting for tanks are safe and will not hurt your fish.

Do Fish Like LEDs?

The evidence is not strong enough to prove that a fish can distinguish the difference between natural, artificial, LED or other types of lighting.

Fish can however, tell the difference by how bright a light is. The brighter the lights, the more harm it can cause your fish and aquarium life. You may notice the following issues:

  • heat rising in the tank
  • fish acting fearful or lethargic
  • algae overgrowth
  • plant leaves overexposed or burnt 
  • erratic swimming patterns of your fish
  • lack of appetite
  • increased aggressiveness
  • excessive hiding

With any lighting option, the best bet is to allow your aquatic life the space and destinations in the tank that offer shade in the form of plants or decorations.

Why Do People Use LED Lights for Aquariums?

LED lights are a common and cheaper solution than many other professional systems including UVB lights. They offer safety through excessive testing to prove that they don’t hurt your fish or other captive animals that we care for.

We can adjust the setting and brightness while putting these LED lights under set timers to make sure we never overdo it. The top options for tank lights include:

  • standard sized fluorescent bulbs
  • compact fluorescent bulbs
  • metal-halide lights
  • LED lights
  • incandescent bulbs 

Incandescent bulbs give off too much heat. Metal-halide and LED lights offer full spectrum lighting, but the former also produces more heat that we don’t need or want if we are running heaters with steady temperatures that our aquatic life rely on.

How Much LED Light Will My Fish Need?

You can decide on the amount of LED lighting your fish need based on the species and the location of your tank. You may also have enough indirect sunlight or indoor room lighting to not need LED lights.

8-12 hours is the minimum amount of time your aquarium should be receiving lights. The easiest way to ensure this is by setting a timer to turn off the lights at night in case you forget.

Most fish follow a diurnal cycle and need rest at night like we do.

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What Are the Pros and Cons of LEDs for Fish?

It’s a good time to discuss the benefits and disadvantages to using LED lights for your aquarium. Here we go:


  • Less energy consumption
  • Low heat
  • Longer lifespan
  • Adjusted light intensity
  • Various color options
  • Expansive light coverage


  • Lack of availability
  • Costs not fixed
  • Not enough lighting for many types of plants

Less Energy Consumption

Standard bulbs consume more energy than LED lights. You will save on your power bill by up to 80%. Even if you pay more for these LED lights, you will make your money back and more in the long run off the savings in your power bill.

Low Heat

Florescent and incandescent bulbs produce more heat. The extra heat can stress out your ecosystem and fish within,. You will not be able to rely on this heat to be consistent and it could be harmful for your fish and their lifespan.


LED lights are safe for your fish and could provide them with a longer lifespan in a tank that doesn’t overheat. The lifespan of LED lights outlast most other bulbs. Due to their long life, they are a great option to replace your standard bulbs,

Adjusted Light Intensity

You can replicate the natural setting of different plants or aquatic life by adjusting the intensity of the lights. You can create a dimmer setting in the early evening and at dawn.

You can simulate moonlight at night. Playing around with intensity adds an extra element of control and fun in this hobby while keeping your fish more calm and relaxed.

Various Color Options

The variety of LED light colors can help your fish look more vibrant. You’ll find LED lights sold by Kelvin units or spectrum. This way you can pick your colors and brightness accordingly.

For example, 8,000 Kelvin Units white spectrum enhances red, orange and yellow fish colors while increasing photosynthesis in your plants.

Expansive Light Coverage

LED strips can cover the full length of your tank. You can create your own DIY setups. The ability to create and design your light coverage makes LED lights more appealing.

Lack of Availability and Cost

Not all LED lighting systems are going to be available at your local retailers. Some online companies will have oversold the most popular types that many hobbyists wish to buy before you get the chance.

The cheapest options could be sold out. Some LED units are simply more expensive than conventional lighting systems, but they will pay you back with overall long-term use by lowering power bills.

Not Enough Lighting for Some Plants

Not all plants will benefit from LED lights. Underwater plants may not get the lighting they need for photosynthesis to occur. You may have to search for more powerful LED lights or purchase plants that do not require as much light.


LED lights are proven safe for fish. Any disturbance due to LED lights can be fixed by keeping a dimmer setting, lower Kelvin units.  Frequent periods or extended periods of lights at night should be reduced to equal 8-14 hours of darkness.

Adjust accordingly for the needs, size and design of your tank.  Your fish should thrive under these LED lightning options.

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.