Why Do Goldfish Change Color? 8 Most Common Reasons Here

Have you ever noticed your goldfish in your aquarium changing colour? Are you wondering why do goldfish change colour, or why they sometimes turn brown due to changes in pigmentation?

It may seem like a small thing, but understanding the reasons why goldfish change colour and pigmentation is crucial for aquarium pet owners.

Author note: I will cover everything you need to know and do below regarding your diet, life, and test.

Why Goldfish Change Color

Goldfish can change color due to several factors, including genetics, environmental conditions, and age. Pigment cells are responsible for the colour of goldfish and can change over time.

The colour change can be more pronounced in an aquarium due to the controlled environment. Sometimes goldfish can even turn black due to changes in their pigment cells.

why goldfish change color

1. Natural Process

Goldfish are known for their vibrant colors, which are determined by the pigment cells in their skin. As they age, these cells can change the color of the fish due to the way light interacts with them.

Young goldfish often have a different colouration than adult fish, and some species may even change colours multiple times throughout their lives. Metallic goldfish like the common goldfish may start out with a dark gray or black color before developing their signature golden hue.

2. Genetics

Genetics plays an important role in determining the color of a goldfish. Different genes control the production of pigments responsible for various colors in fish, such as red, orange, yellow, black, and white.

These pigments are produced by specialized cells that respond to light and chemical signals. Breeders can selectively breed goldfish to produce specific colors or patterns by choosing individuals with desirable traits to mate. This has led to the development of many different types of fancy goldfish with unique colorations and patterns.

3. Environmental Factors

Environmental factors can also play a role in causing changes in goldfish coloration. For example, exposure to sunlight can intensify the colors of some fish species like koi carp due to increased pigment production.

Changes in water quality or temperature can also affect how vibrant a fish’s colors appear, and high levels of ammonia can cause black discoloration. In some cases, stress or disease can cause a goldfish’s color to fade or change dramatically.

4. Different Types of Pigments

The different types of pigments responsible for producing various colors in goldfish include melanin (black pigment), carotenoids (yellow-orange-red pigments), pteridines (red-orange-yellow pigments), and guanine (iridescent silver-white pigment).

The combination and concentration of these pigments, along with light, determine the overall appearance and hue of a fish’s coloring. Ammonia levels can also affect the vibrancy of the colors.

5. Stress

Goldfish are known to change color suddenly due to stress caused by changes in the tank environment, such as fluctuations in temperature, light, and water quality issues like ammonia. When stressed, goldfish release hormones that affect their pigmentation and can cause them to appear pale or even develop black spots on their scales. To prevent this from happening, ensure that your goldfish’s tank is properly maintained with regular water changes, appropriate temperature levels, and proper lighting.

6. Seasonal Changes

Seasonal changes can also impact the color of your goldfish. During the winter months, many goldfish will lose some of their vibrancy due to decreased sunlight exposure.

During the spring and summer months when there is more sunshine, you may notice that your goldfish’s colors become brighter and more vibrant.

Some species of goldfish have been known to change color seasonally as part of their natural breeding cycle. Additionally, exposure to high levels of ammonia can cause black spots to appear on a goldfish’s body.

7. Diet and Nutrition

The food you feed your goldfish can also play a role in its coloration. Certain nutrients like carotenoids found in vegetables like carrots can enhance the intensity and vibrancy of a goldfish’s colors. On the other hand, a diet lacking in essential nutrients can lead to paler colors or even cause your fish to lose its color altogether.

Exposing your goldfish to too much light can cause stress and negatively impact their coloration. It’s important to monitor ammonia levels in your tank as well, as high levels of ammonia can lead to black spots on your goldfish’s fins and body.

8. Age

As your goldfish ages, it may gradually shift colors due to natural aging processes. Some species may develop darker patches on their scales or fins over time, turning black, while others may become lighter overall as they age.

It is important to note that ammonia levels in the tank can also affect the color of your goldfish over time.

Why Goldfish Turn White

1. Genetic Mutations

Goldfish are known for their bright and vibrant colors, but sometimes they can turn white or pale. This change in color can be due to genetic mutations that cause the fish to lose pigmentation. These mutations can occur naturally or through selective breeding.

Some goldfish breeds, such as the celestial eye and bubble eye, are more prone to developing these mutations. In rare cases, goldfish can also develop black coloration due to genetic mutations.

2. Stress-Induced

Another reason why goldfish may turn white or lose black color is due to stress-induced loss of pigment. When a fish is stressed, it releases cortisol which can cause a loss of melanin production resulting in white patches or spots on its body and the disappearance of black color.

Common causes of stress in goldfish include poor water quality, overcrowding, and sudden changes in temperature.

3. Illnesses

Illnesses such as ichthyophthiriasis (white spot disease) can also cause white spots on the skin or fins of goldfish, while bacterial infections and fungal infections can lead to changes in color. In addition, black spots may also appear on the skin or fins of goldfish due to certain illnesses.

This parasitic infection is highly contagious and can quickly spread throughout an aquarium if not treated promptly.

4. Aging Process

Lastly, some species of goldfish may develop black spots on their scales as they age and turn white. For example, the shubunkin variety often has blue-gray scales when young but gradually develops black spots before turning silver-white as it gets older.

Why Goldfish Turn Black

Goldfish, like many other animals, produce melanin. This pigment is responsible for the coloration of their scales and skin. When a goldfish produces an excess amount of melanin, it can lead to black or dark-colored scales. This is often seen as patches or spots on the fish’s body. The reason for this excess production can be due to genetics, environmental factors, or health issues.

1. Crossbreeding

Another reason why goldfish turn black is crossbreeding with other species. Some species of fish that are bred with goldfish have genes that produce black offspring. This means that if a goldfish breeds with one of these species, its offspring may have black scales from birth.

2. Environmental Factors

Environmental factors such as water temperature, pH levels, and lighting conditions can also trigger melanin production in goldfish, leading to black color change.

If the water temperature is too low or the pH level is too high or low, it can cause stress on the fish’s body. In response to this stress, the goldfish may produce more melanin than usual, resulting in a black color change.

3. Health Issues

Finally, health issues can also cause goldfish to turn black. One common issue is ammonia poisoning caused by poor water quality in their tank or pond. Ammonia buildup in the water can lead to blackening around the gills and other areas of the fish’s body.

Does Disease or Parasites Cause Goldfish Color Change

Goldfish are one of the most popular fish species kept as pets. They are known for their bright and vibrant colors, which can change over time. As a goldfish owner, it is essential to understand why your fish’s color might change, including the possibility of turning black.

1. Parasitic Infections

Parasitic infections are one of the primary causes of goldfish color change, including black discoloration. These infections can be caused by flukes, lice, or anchor worms that affect the skin’s surface. When these parasites attach themselves to the fish’s skin, they cause black discoloration, irritation, and other symptoms.

Some common signs of parasitic infections in goldfish include:

  • White spots on fins and body
  • Redness or inflammation on the skin
  • Scratching against objects in the tank
  • Abnormal swimming behavior

If you suspect that your goldfish has a parasitic infection or black color change, you should quarantine them immediately and treat them with an appropriate medication.

2. Bacterial Infections

Bacterial infections can also lead to changes in a goldfish’s coloring. These infections can cause redness, inflammation, ulcers, or black spots on the skin that affect its appearance.

Some common signs of bacterial infections in goldfish include:

  • Red streaks on fins and body
  • Ulcers on the skin
  • Loss of appetite
  • Lethargy

If you suspect that your goldfish has a bacterial infection, you should isolate them from other fish and treat them with an appropriate antibiotic medication. Look out for any black color change as it may indicate a serious condition.

3. Fungal Infections

Fungal infections are another possible cause of color changes in goldfish. These infections often produce cotton-like growths on the fish’s skin that alter its coloring, including turning it black.

Do Dead Goldfish Change Color

Goldfish are popular pets that are easy to care for, but they can be quite delicate creatures. One of the most common questions that pet owners ask is whether dead goldfish change color, particularly if they turn black.

1. Decomposition Process

When a goldfish dies, its body begins to decompose. This process causes changes in the fish’s color and texture, but it does not turn black. As the fish’s body breaks down, it releases gases that cause bloating and discoloration. The scales may also become loose or fall off entirely, but they do not turn black.

2. Bacterial Activity

Bacteria play a significant role in the decomposition process of a dead goldfish, turning its body into a black mush. They break down organic matter, releasing enzymes and gases that cause discoloration and foul odors. The bacteria can also produce toxins that can harm other aquatic life in the same tank.

3. Environmental Factors

The rate at which a dead goldfish decomposes depends on various environmental factors such as water temperature, pH levels, and oxygen levels. Higher temperatures accelerate decomposition while lower temperatures slow it down. The color of the water, whether it is black or not, does not affect the rate of decomposition.

4. Time Elapsed

The extent of color changes in a dead goldfish will depend on how long it has been since death occurred. Typically, within hours of death, there will be visible signs of discoloration or bloating due to bacterial activity and gas buildup.

Does Poor Water Quality Affect Goldfish Color

High Levels of Ammonia, Nitrites, or Nitrates

Goldfish are known for their vibrant colors, but those colors can fade if the water quality in their tank isn’t up to par. One of the primary culprits is high levels of ammonia, nitrites, or nitrates in the water. These compounds are produced by fish waste and uneaten food, and they can build up quickly if not removed through regular water changes.

When ammonia levels get too high, it can lead to stress-induced loss of pigment in goldfish. This means that their colors will start to fade or become less vibrant over time. Nitrites and nitrates can also contribute to this problem by interfering with a goldfish’s ability to absorb oxygen from the water.

Low Oxygen Levels

Another factor that can impact a goldfish’s color is low oxygen levels in the tank. When there isn’t enough oxygen in the water, it can affect a goldfish’s metabolism and overall health. This can cause them to become sluggish and lose some of their vibrancy.

To ensure that your goldfish have plenty of oxygen in their tank, make sure you have an adequate filtration system and consider adding an air stone or bubbler. You should also avoid overcrowding your tank since too many fish can deplete the available oxygen.

Heavy Metals or Toxins

Goldfish are sensitive creatures, so even small amounts of heavy metals or toxins in their environment can affect their coloring. For example, copper is toxic to most fish species at even low concentrations. If there is copper present in your goldfish tank due to contaminated tap water or other sources, it could cause them to change color.

Other toxins that can affect goldfish coloring include chlorine, chloramine, and ammonia.

Can Goldfish Change Back to Their Original Color

In conclusion, goldfish can change color due to various reasons such as genetics, age, environment, and diet. While some color changes are temporary and reversible, others may be permanent.

For instance, if your goldfish turns white or black due to genetic factors or old age, it is unlikely that they will revert to their original color.

However, if the color change is due to poor water quality or a disease/parasite infection, improving the water conditions and treating the underlying issue can help restore your goldfish’s original color.

It is important to monitor your goldfish’s behavior and appearance regularly to catch any potential issues early on.

To maintain healthy and vibrant-colored goldfish, ensure that you provide them with a suitable environment that includes clean water, proper filtration system, adequate space, and a balanced diet.

Avoid overfeeding your goldfish as this can lead to health problems and affect their natural colors.


Q: Can stress cause a goldfish to change color?

A: Yes, stress can cause a temporary color change in goldfish. If you notice your fish turning pale or losing its vibrancy suddenly after introducing new tank mates or changing their environment drastically, it could be due to stress.

Q: How long does it take for a goldfish’s color to change?

The duration of color change in fish depends on the underlying cause. Some nacreous goldfish may experience gradual colouring over time, while matte goldfish may suddenly show signs of being diseased within days or weeks.

Q: Is it normal for my goldfish’s color to fade during winter?

A: Yes, it is common for some types of goldfish such as koi carp to lose their bright colors during colder months when they enter hibernation mode. However, this should not last more than a few months.

Q: Will adding plants in my aquarium affect my goldfish’s color?

A: Adding live plants in your aquarium can help improve water quality and create a natural environment for your goldfish. However, some plants release tannins that may turn the water brownish, which can affect the fish’s color perception.

Q: Can feeding my goldfish with certain foods change their color?

A: Yes, feeding your goldfish with food containing carotenoids such as spirulina or krill can enhance their natural colors. However, overfeeding or feeding low-quality food can lead to health problems and affect their overall appearance.


Hello, I'm Jason. I'm the guy behind HelpUsFish.com. I volunteer at my local fish shop and I created this site to offer tips and advice on the fish I care for.