Do Neon Tetras Glow in the Dark?

If you are a fish lover, then you quite likely have had neon tetras in your aquarium at some point. Neon tetras are very popular today because of their beautiful colors. They can be found in almost all pet stores that sell fish. If you own neon tetras, then you have a unique breed of pet fish that is worth keeping. Neon Tetras are bright and appear almost luminous, so you may be wondering “do neon tetras glow in the dark?”

The answer to whether neon tetras glow in the dark is both no and yes. 

No, because neon tetras are not bioluminescent – a bioluminescent fish can produce and emit light by itself. (source)

And yes, because their iridescent blue color has highly reflective scales. It can absorb light which is then reflected back on the viewer to produce a glowing effect; neon tetras need an outside light source to reflect.

Under the glow of a black light, neon tetra looks great. The shiny blue stripe down their bodies glow. Their skin also glows. So, if you are viewing neon tetras with a black light on, you will be seeing the fish glowing in the dark. Under a black light, fluorescent colors glow.

What are the colors of the neon tetra?

People are drawn to the neon tetra because of their sensational coloring.

The neon tetra has a back that is light blue and an abdomen that is a silver-white. There is a shimmering blue horizontal stripe along each side of the fish. This stripe goes from its nose to the base of the adipose fin. The adipose fin is the small rounded fin in between the tail and the dorsal fin.

It also has an iridescent red stripe which goes from the middle of the body up to the tail of the fish. These bright, shiny colors enable the fish to locate each other in murky water conditions. Some neon tetras develop a dark olive-green sheen lining on their backs. But this is something rare.

Most of the parts of the fish including the fins are transparent except the stripes. At night, these stripes turn to gray or black. This happens when the fish rests. When they become active in the morning, the colors become bright again.

Neon tetra are an inch and a half long. This is the usual size of an adult. However, if the fish is smaller than this, then it will have brighter colors. Its colors make up for their small size.

When you add neon tetra to your aquarium, it is like seeing magic because of their sensational colors, especially if you add them to a tank filled with different kinds of fish. Your whole aquarium would be decorated with their multicolored bodies.

The female neon tetra has a large belly. This is why the iridescent stripe is bent. The male neon tetra, on the other hand, has a straight stripe.

Neon tetras are cool-looking fish. Their bright colors really get your attention. You can easily tell when they are around. As we have mentioned earlier, they don’t give off their own light, but you can definitely see them in the dark because they are fluorescent and they glow. When light hits them, they shine really bright.

Neon tetra is one of the most recognizable fish among fish lovers because of their color combination.


do neon tetras glow in the dark

Why are fish born neon?

The neon colors of neon tetra come from their genes and physical makeup. These colors do not necessarily come from the food they eat or from their environment. So, if a fish is not neon at birth, it will never become neon by eating or through the environment. The fish needs to have DNA or genes that would allow for that. (source)

One of the reasons for their neon color is to attract prey. Their bright colors will dazzle the prey and think of them as prey. Actually, they are headed for the mouth of the predator.

Their neon color is also for their defense. Neon colored fish are actually schooling fish. They usually fall prey to other larger fish. So, when these neon-colored fish are traveling together by the hundreds, the bright, dazzling colors will confuse their predators and give up. Their bright colors are a defensive mechanism of schooling fish.

(Read about what fish glow in blacklight here)

What factors affect the color of neon tetra?

One of the factors that affect the neon tetra’s color is food. If you feed your neon tetra with the right kinds of food with the right nutrients, then their colors will become much brighter and stronger.

The amount of fish in the school is also a contributing factor to the color of neon tetra. It is proven that solitary neon fish do not have nearly as much color as neon fish that live in schools. And as we have mentioned earlier, it is their natural defense.

The neon tetras natural habitat is the warm rivers of South America. These rivers run through thick forests that have dense canopies. And natural daylight is blocked for the most part. So, the river waters are dark. In these waters are lots of fallen leaves, tree roots, and vegetation. The vivid colors of the neon tetras help them to identify their fellow fish in these waters.

(If you want to know more about how neon fish get their color, click here.)

Why do the colors of neon tetras fade?

It is important tank clean and well cycled if you want to keep the colors of your neon tetra looking beautiful.

Sometimes, the vivid blues and reds start to dull. This can be alarming to any fish lover. If your neon tetra’s colors are fading, you need to know why.

One of the reasons for the dull color is when neon tetra gets stressed. Having a single neon tetra in your aquarium can greatly stress it out. Neon tetras like to be part of a group. Being alone will stress them out. When it gets stressed the colors will start to fade. This is why it is important that if you are going to have neon tetra in your aquarium, you should have enough to form a school.

Another reason why the colors of neon tetra pale is when the aquarium is brightly lit and there are very few plants in it. In the place where they originated there are lots of plants for cover and the environment is shaded.

Neon tetra may also exhibit a slight color fade when they spend a lot of time in the darkness or at night. This is something normal so this should not be a cause for alarm.

One interesting thing about neon tetra is that they are transparent. This greatly helps them hide from their predators. If there is a real threat, they can turn off their red and blue iridescent hue. This can help them stay safe.

Other instances when the color fades are when the tetra is sleeping or when it is sick.

Do neon tetras sleep

How do you care for neon tetras?

If you are putting them in an aquarium, make sure that you try to replicate their natural environment.

The aquarium should be at least 40 cm in length. It needs to have warmth from a heater and a filter so that their waste is broken down. Lighting should be subdued. This can even help their colors become more intense.

If your neon tetras are new and they start to act weird, do not be alarmed. Neon tetras are very sensitive to change. It would take them time to cope and get used to the new conditions of the water, the tank, and the temperature. In time, they would get used to their new home.

Make sure you prepare your aquarium efficiently to be suitable for them before adding them in. You need to fully prepare your tank and make adjustments in the water temperature and other important things so that you can provide them with a healthy atmosphere. Neon tetra are sensitive, delicate little fish.

Make sure that the water is soft and acidic. You can add blackwater extracts so that they can easily adjust to the darkness of the water. Blackwater extracts also softens the water and makes it acidic.

Make sure to add a lot of plants in your tank so that you can replicate their habitat which is filled with many plants and roots. When this is the case and you can make your tank resemble a bit with their natural habitat, your neon tetras will start acting normal. Their colors will also start to shine brightly.

(Read our guide on caring for neon tetras here)

What are the lighting requirements for neon tetra?

Neon tetras need lighting 12 to 14 hours each day. This will help them maintain a proper internal process that regulates their sleep-wake cycle.
It is best to have a timer so that your fish can settle into a routine. Make sure your lighting is subdued.

Final Thoughts

If you are planning to have an aquarium with neon tetra, make sure to choose those with the most vibrant and bright colors. And don’t just get one – have at least a dozen tetras because they are schooling creatures that cannot live alone.