Are Fluorescent Lights Bad For My Aquarium Fish Or Plants?

Being a dedicated aquarium owner, I’m sure you care a great deal about your fish, and you’d want the best for them.

The Ultimate Guide To Saltwater Fish…

Every aspect of the tank has to be right, including the cleanliness, and of course the lights.

Out of concern, you may ask – Are fluorescent lights bad for my aquarium fish or plants? Well, the general answer is no, fluorescent lights are not bad for your aquarium fish or plants. As a matter of fact, fluorescent lights are a lot better than incandescent bulbs, since they are cheaper and produce less heat. Heat makes water evaporate faster.

If you’re a first-time aquarium owner and you’re not too sure what the purpose of an aquarium is, or what types of lights are best, then keep reading. In this article, I’ll be giving you some really helpful information regarding aquarium lighting.

What Are The Benefits Of Aquarium Lighting?

Before we get into what type of lighting is best for your aquarium, we need to have a clear understanding of what lighting does for your aquarium.

The major purpose of aquarium lighting is illumination. Aquarium lights give your tank a nice, beautiful glow. They also make the colors on your fish more vivid.

Another function of aquarium lights is photosynthesis. Live aquarium plants need proper lighting to go through this process. The process involves converting light to energy, and carbon dioxide into oxygen.

Since plants depend on light for energy, it is very important that your tank is adequately lit up.

Types Of Aquarium Bulbs/Terms

There are several options when it comes to choosing aquarium lighting. For you to fully know what makes them distinct, you should first be acquainted with a few terms and types.

Different bulb types give out light at different wavelengths from different parts of the light spectrum. Below I will be looking at the major types of bulbs for aquarium lighting.


Actinic light is derived from the blue end of the color spectrum. Commonly, this type of lighting is preferred for cutting through deep water.

This is the major reason actinic lighting is commonly recommended by Aquarium experts for large, saltwater tanks. Actinic bulbs can be sometimes sold as 50/50 bulbs, and they give out a nice combination of blue and white light.

Full Spectrum

A full-spectrum light gives out light at all the wavelengths visible to the human eye.

Full-spectrum light bulbs can also be called daylight bulbs. This is because the light they produce can be compared to natural daylight.

Full-spectrum produces light at all visible wavelengths, and as far as general-purpose aquarium lighting is concerned, they are a great choice.

Color Enhancing

Another term associated with both actinic or daylight bulbs is “color enhancing”.

These bulbs are termed “color enhancing” because of their ability to make the colors of both aquarium fish and plants more vivid or pronounced.

These bulbs basically emit light from the warmer end of the spectrum, and they are suitable for both freshwater tanks and saltwater tanks.


Fluorescents are one of the most common bulb types used by a wide range of aquarium lighting systems. These include standard fluorescent, compact fluorescent, T-5 HO and VHO.

Fluorescent bulbs function as a gas-discharge lamp, they use electricity to trigger the mercury vapors which are contained in the bulb to emit light.

Different types of fluorescent bulbs come in different wattages and intensities of light. These range from as low as 10 watts, to as high as 1,000 watts.


Incandescent bulbs emit light using electricity to heat a filament wire found inside the bulb. Here’s how it works – When the wire begins to heat up, it starts to glow, and begins to produce light.

These bulbs are not the best when it comes to aquarium lighting, mainly because they produce excessive heat. However, they can be found in small novelty aquariums, combined as a heat/light source.

Power Compact

These are high-powered bulbs which have almost the same lumen-per-watt rating as T-5 bulbs, which is usually around 60 lumens per watt.

These bulbs can be found in 3 different types. These include:

  • Straight-pin
  • Square-pin
  • Self-ballasted screw-in

Power compact bulbs are not just high-powered, they are also very versatile. For this reason, they are a very popular choice among aquarium owners.


LED lights are not actually light bulbs, rather, they are light-emitting diodes.

This type of lighting has grown popular among aquarists, this is because they are very energy efficient and they last long.

LED lights produce a very distinct “shimmering” effect in the tank, which significantly enhances the tank’s appearance, and they are also capable of producing a “lunar” effect, which is very ideal for nocturnal aquarium fish.

Lighting Options by Tank Size

So, now that you’re aware of the different lighting options for your aquarium, you can now choose the perfect lighting for your tank, not just based on efficiency, but based on the size of your tank as well.

When choosing lighting for your tank based on size, don’t just consider the length and volume, keep the depth of the tank in mind as well.

There are lights that are suitable for standard small tanks, but you should check to see if they are intense enough to penetrate water that goes deeper than 18 inches.

For those aquarium owners who keep floating live plants, bear in mind that these plants will reduce the intensity of the light from getting to other parts of the aquarium.

Will My Fish Die Without Aquarium Light?

As much as aquarium lighting brightens up the tank, and enhances the colors of your fish, they can live without it. So the answer is no, your fish will not die without aquarium light.

Experienced aquarists have actually advised you should turn off the lights at night, as too much of aquarium light promotes algae growth.


Fluorescent lights and aquarium lighting in general help your tank look beautiful, but most importantly, they are needed by the live aquarium plants for the purpose of photosynthesis.

I trust your question: are fluorescent lights bad for my aquarium fish or plants, has been answered by this article.

Take care!

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