Why Do Tetras Lose Or Change Their Color? (Main Causes)

Why Do Tetras Lose Or Change Their Color? (Main Causes)

Image of cardinal tetras with beautiful colors

The two main causes of color change in tetra fish are stress and disease. Extended exposure to bright light, loneliness, the presence of predators, and changes in water chemistry put a lot of stress on tetras. Pathogen-induced infections and diseases also cause their colors to fade over time.

Let us explore each of these conditions in closer detail.

Causes Of Color Change In Tetras

Do you know how tetras get their exquisite colors?

It is because they have cells called chromatophores that absorb light rays and produce incredible color combinations.

Now, most types of fish have chromatophores.

However, the visual effect that they create depends on how these cells are arranged.

In tetras, the chromatophores produce various effects like iridescence, fluorescence, and reflection.

The result is an incredible and vibrant color that lights up the scene.

So, exposure to light plays a significant role in deciding a tetra’s colors.

Tetras pale or lose their bright color when they are subjected to stress.

Let us look at the different stressors that affect these fish.

Exposure to light.

We just saw that chromatophores are responsible for the beautiful colors of tetra fish.

Now, in the wild, the tetras live in shady environments with lush plant growth and vegetation.

It is most comfortable in tanks that recreate this natural environment.

Tetras will look their best, with exuberant colors, in such a setting.

Hence, a brightly lit tank is an unnatural environment for these fish.

They experience stress in such a setting. Consequently, their colors fade.

You can solve this problem by using soft light in the tank and placing plants for shade.

A planted tank will also give the tiny fish plenty of hiding spots.

When tetras are secure and happy, they regain their original colors.

Swimming solo.

Tetras are schooling fish. Hence, it is ideal to keep them in groups. The larger the group, the happier the fish are.

An ideal school size for an aquarium would be fifteen to twenty fish.

However, if you cannot keep so many fish together, you should at least keep them in groups of five or six.

Your tetra will not be happy without any company. A solo tetra is a sorry creature.

It will experience a lot of stress. It may subsequently lose its beautiful colors.

Changes in water parameters.

The ideal habitat conditions for tetras include a temperature range of 70°F to 80°F and pH levels between 6 and 6.5.

Tetras are very sensitive to changes in water parameters.

They do not easily adapt to pH level changes and the presence of toxins in the water.

Hence, tetras are best placed in established and well-cycled mature tanks. They will not adjust easily to newly cycled tanks.

Sudden changes in water chemistry can cause immense stress to these fish.

Higher levels of ammonia or nitrites in the water also cause stress.

In an unhygienic tank, tetras will quickly lose their colors. Continued exposure to such an environment may even be fatal.

The presence of predators.

Mixing different species of fish in the same tank can be a tricky affair.

Unless the fish are compatible, the peace of the tank will be disrupted.

Tetras, being small fish, are vulnerable to attacks from large, aggressive fish.

Cichlids, bettas, and angelfish are common aquarium fish that tend to attack or threaten tetras.

Since these fish will treat the tetras as prey, the smaller fish will be under constant stress.

If your tank does not have enough hiding places, it will be vulnerable. It can make them lose their beautiful colors.

Keeping tetras in schools will reduce their stress to a great extent.

Nonetheless, it is better to place these fish with peaceful, community fish that will not bully or attack them.

They will also be better off in tanks where they do not have to compete with other fish for food and space.


Most of the time, the loss of color in tetras is caused by stress. You can usually reverse such problems by removing the stressor.

However, tetras may also lose their colors due to diseases.

Since tetras are sensitive to toxins, they can become ill when the surrounding water is dirty.

They are also prone to illnesses caused by common pathogens like bacteria and protozoa.

The “neon tetra disease” is a very common disease that affects tetra fish. It is a sporozoan disease with no remedy.

The easiest way to avoid such diseases is by keeping the tank clean.

Invest in a good filter and regularly cycle the tank to make it an ideal living place for your tetras.

You should also be on the lookout for any signs of illness and tackle it promptly.

Administer suitable medication and quarantine a sick tetra to prevent the illness from spreading to other members of the school.

Proper nutrition and care will also help tetras live long and retain their lovely colors.

Almost all types of tetras lose their colors due to the same factors.

Nonetheless, let us look at each of the varieties and ascertain how they are affected.

Why Do Neon Tetras Turn Black Or Brown?

Neon tetras are very sensitive and small. They are easily affected by stress and highly vulnerable to changes in water parameters.

Neon tetras lose their colors and look dull when they are stressed.

You may like to check the pH of the tank to find out if their color change is linked to an ammonia spike.

Ammonia burns and causes the fish to turn black. Tetras may also turn brown or black if they are affected by a disease.

In some cases, the color change may even be temporary. Your neon tetra may regain its original coloring without any intervention.

Nonetheless, keep an eye on your pet to make sure that any black color that appears does not grow and get out of control.

Why Do Neon Tetras Lose Their Color At Night?

Neon tetras tend to pale and look dull at night.

However, this is not a cause for alarm because it is a protective mechanism that Mother Nature has blessed them with.

The pigment-producing chromatophores on the tetra’s body produce bright colors when they are close together.

It happens during the day when the fish are active and energetic.

Neon tetras are attuned to a day-night cycle, and they rest in the night.

During this time, the light-sensitive cells relax and stretch out. Hence, their color becomes dull.

Why Do Cardinal Tetras Lose Their Colors?

Cardinal tetras tend to lose their color when they are stressed or sick.

However, their colors will also fade for no apparent reason at night.

As a pet owner, you may be shocked to find the bright red streak of your cardinal tetras missing at night.

However, there is nothing to worry about. It is normal for cardinal tetras to take on a pale, ghastly appearance at night.

This natural adaptation allows the fish to escape large predators when they are resting.

Due to their pale appearance, they look weak and dying. So, they do not appeal to predators.

During their resting period, they may also not move too much.

However, cardinal tetras will usually bounce back to their original color in a day.

Why Do Black Skirt Tetras Lose Their Color?

Black skirt tetras lighten up when they are under stress or faced with an illness.

Something as simple as a water change or gravel clean can cause their color to fade temporarily.

However, they will usually regain their dark color when they recover from the illness, or you get rid of whatever is causing stress to them.

When the conditions in the tank are favorable for their existence, black skirt tetras retain their dark color.

However, the fish tends to become gray as it grows older. It is part of the natural aging process.

However, if your black skirt tetra is young and losing color for extended periods, take a closer look.

It could signal poor water conditions. They will also pale when the lights are off and become darker during the day.

Why Do Serpea Tetras Lose Their Color?

Serpea tetras lose their color with every water change because they are sensitive to water parameters.

However, dull colors for extended durations can indicate stress or illness.

These fish pale when other fish bully them. It does not even have to be a predatorial fish.

A single aggressive serpea in a tank can bully other fish in the school and cause them to lose colors.

Serpeas are also affected by dirty water and excess light.

If they are continuously subjected to any source of stress, they will ultimately pass away.

Another reason for a serpea tetra to become dull is sickness.

Infections caused by germs can make them lose their lively colors and appear dull.

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