Freshwater Fish

What Are Those Black Spots On Your Goldfish? Alarming Or Easy To Cure?

Our pets are members of our family, so it is a given that we will care about the state of their health. Your goldfish might require less care than furry creatures, but they deserve as much tender loving care as you can give.

This species is relatively low maintenance and will thrive in a healthy environment and good food. But with such vivid scales, it will be quite shocking to notice certain drastic changes to its appearance.

It is only natural to worry when you see that your goldfish is turning black. After all, these dark spots look so different from the normally bright colors of its body.

We know that you will be worried about what on earth is going on with your pet.

However, you should not be rash and go into a panic. You see, there are several reasons behind the appearance of these black spots on goldfish.

By the end of this article, you should be able to figure out which one is causing this condition and what to do about it.

What Do You Need To Know About Goldfish?

Goldfish have earned a reputation for being “easy” to look after when it comes to fish. They are also easy to find since most pet stores out there sell them.

Many people like the fact that they easily adapt to a new environment.

There is no doubt that the most distinctive quality of this fish is its gold color. This is the result of millennia of selective breeding. Of course, certain breeds deviate from this. It is always good to check with the seller to see what kind you are getting.

In any case, it can be alarming when you notice the orange coloring turning black. Most people will take this to mean that there is something wrong.

As a rule of thumb, it is more common for goldfish to turn white than black. If you start to notice black patches or spots on goldfish, it is time to put on your detective hat to see what might be causing the condition.

It is possible that this is a sign that there is an internal problem. But on the other hand, it might be completely harmless.

However, there are various factors at play here. For the sake of your goldfish, get it checked out right away to learn whether or not this is a serious problem.

Is It Normal To See Color Changes In Goldfish?

In reality, it is normal for goldfish to develop changes in their coloring. As they age, the color of their body naturally changes.

Keep in mind that this typically happens during the first year or two. Black goldfish might turn orange or yellow as they grow older, while others lose the black markings on the bodies and fins.

Knowing this, remember that it is atypical for a goldfish to change from orange or yellow to black.

Do Goldfish Turn Black When Sick?

As we have mentioned earlier, there are many reasons your goldfish is turning black. Without a doubt, there are several that are more serious than others. Goldfish might turn black when it is sick, although this is not the only possibility out there.

Which Parts Of The Goldfish Normally Turn Black?

Goldfish typically get black spots on the tail. Aside from this part of the body, you might also notice the same thing happening to the mouth of the fish and the fins. As a matter of fact, black spots on goldfish can appear anywhere on the body of your pet.

It is possible that it is nothing to be worried about, although it is worth checking out since it might also indicate a serious health condition.

black smudge in goldfish

Reasons Why Do Goldfish Turn Black

Are you wondering why some goldfish developed black spots? Here are some of the most common reasons behind this condition:

Goldfish Genetics

In case you didn’t know, there are a lot of blended breeds of goldfish on the market. This means that they were not bred to retain specific characteristics and features.

“Mixed” species are not guaranteed to maintain a specific coloring, so some might change colors over time. Natural coloration changes can happen gradually, often with lighter areas appearing alongside the darker areas.

Dim Lighting

The color of your goldfish is affected by the location, lighting, and environment. There are different types of cells found in the scales that result in the production of different colors.

Melanin is the primary compound associated with dark complexions in people, and some cells produce it.

Goldfish staying in dim and dull environments usually experience a darkening of their scales. For some, this only affects their fins. However, extreme cases involve completely turning black! This is not considered a health issue since it does not affect the well-being of your fish.

If you want to prevent this from happening, you can introduce more brightness to the tank with additional lighting. After several weeks, the color should revert to the original.

Dark Decorations

It is a good idea to avoid black decorations and backgrounds in the tank in the same vein. After all, they will stimulate the production of melanin in the fins and other parts of the body. This can be addressed by adding bright and colorful pieces of decoration inside the tank.


You should be careful not to overfeed your goldfish. This typically happens when the goldfish is still unused to the current environment.

What makes this such a big problem is that it increases the amount of waste in the tank. This is then exacerbated by a faulty filter.

Poor conditions brought about by overfeeding can result in fish discoloration, illness, ammonia poisoning, or swim bladder disorder. Therefore, it is of utmost importance to keep an eye on the feeding of your fish. We highly recommend reading up on this topic some more.

It will also be a good idea to take notes about the eating habits of your pet. Do not forget to get rid of food waste right away.

High Ammonia Levels

It is also possible that the fins of your goldfish are turning black due to ammonia burn. Even in small quantities, ammonia can be lethal to your pet. It will suffocate the fish unless it is taken care of right away.

If you notice black spots on the fins and other parts of the body, it might be a warning that there is too much ammonia in your tank.

As a rule of thumb, any level of ammonia should not be present in such an environment. This means that the ideal ammonia level is 0.0ppm. However, levels over 1.0 ppm might cause illness or even kill fish in the tank.

Test for ammonia as soon as possible. The black spots on goldfish mean that the fish is suffering from a skin infection that it is now healing from.

Even though the black fins show that the healing process has commenced, high ammonia levels will continue to damage your pet’s health. It is of utmost importance to resolve this issue right away.

Small Tank

If you have five fish in a 20-gallon tank, they will not have enough space to swim in. When this happens, it might cause black spots on goldfish.

This is an indicator that your pets are experiencing stress from poor living conditions and the environment. Make sure to get an appropriate fish tank to ensure that this will not happen.

Ineffective Filter

Goldfish are known to produce a lot of bioloads. When your filter is not working properly, this might result in a huge ammonia buildup in the tank.

As previously mentioned, this might cause black spots on goldfish. Inspect the filter to see whether or not it is working as it should.


Like any other animal, goldfish also bleed. Black spots on goldfish might form as a result of blood pooling due to a hemorrhage.

This might happen when a pointy object or decoration punctures a goldfish in the aquarium. Ensure that the environment is safe to prevent this from taking place.

Can goldfish lose their black markings

Black Spot Disease

While this is rare for the two reasons mentioned earlier, it is still within the realm of possibility. There is a certain kind of parasite known to infest aquariums.

Known as black spot disease, this condition happens when the parasite is introduced to the environment by hiding in snails.

In case there are snails with the goldfish in the tank, this might be the culprit. It likes to hide below the skin of the fish, lay eggs, and form a hard, black cyst that manifests in the form of black fins.

Another symptom of this condition is when fish start to rub against surfaces and flick the tail. They do this because they are irritated by the presence of the parasite.

You should take the snails out of the tank to remove the parasites and black fins. This should make everything return to normal, although you might have to wait at least a month before you can see the changes.

If the problem seems grave, it might help if you use aquatic parasite treatment to make the problem go away faster. Of course, this is going to be quite costly.

Does Black Spot Disease Kill Fish?

It is a relief to learn that heavy parasite infestations are, in general, relatively harmless to the health of your goldfish. However, you should keep in mind that juvenile fish are at risk for health problems if they experience heavy infestations.

Evidence has shown that they might suffer from physiological stress, excessive blood loss, and maybe even death. It is a good idea to address the root of the problem at the earliest opportunity.

Is Black Spot Disease A Hazard For Humans?

You can rest easy with the knowledge that fish parasites are typically harmless to humans. The only exception to this rule would be the broad fish tapeworm.

This means that we are not at any risk of contracting black spot disease from fish. It might also help to hear that proper cooking is known to destroy parasites, even tapeworms.

What Does Ammonia Poisoning In Fish Look Like?

Fish waste and rotting food in the tank produce ammonia. The presence of it can change the skin of your goldfish.

Ammonia burns are not visible to the naked eye, so we are only alerted to their presence when the levels of ammonia go down. This results in the healing of the skin and turning the burnt patches dark. Inspect your goldfish for black patches on the fins and the rest of the body.

Will Goldfish Recover After Getting Ammonia Poisoning?

While ammonia poisoning might leave long-term effects, goldfish can recover from it. By this, we mean that the fish will survive it and return to normal after some time.

It goes without saying that this only applies if they did not suffer from an intense bout of ammonia poisoning.

Will The Black Spots On Goldfish Go Away?

You might be wondering if your orange goldfish will stay black forever. The truth is that it depends on the cause of the discoloration. In some cases, the goldfish will eventually go back to the original coloring.

There are times when this does not happen, however. Most illnesses, ammonia poisoning, and genetics are known to cause permanent color changes.

If you address the root of the problem, you can expect the black spots on goldfish to go away with enough time. However, this is not the case if you do not fix these issues in due time.

As a matter of fact, things might only get worse after a little while. In the most extreme cases, this might cause goldfish death.

How Do I Get Rid Of Black Spot On My Goldfish?

Essentially, the only way to get rid of black spots on goldfish is to treat the cause. In case you have an infection in the fish tank, give the affected fish a freshwater dip and then a formalin bath.

Keep this treatment going in a quarantine tank. Some people have reported successful treatment with the use of praziquantel. Do not forget to give the main tank a good cleaning and sanitization. After this, use clean, fresh water to refill the tank.

Use stabilizers to treat the water and wait until the environment has stabilized before you return the fish.

It might also be a good idea to ask for professional help courtesy of a local aquarium shop. This way, you can get a proper diagnosis and treat your pet with the necessary medication to give your goldfish the best shot at recovery.

What does fungus look like on goldfish

How to Know If Your Goldfish Is Dying?

We know that the idea of your pet dying is not a comforting thought.

Despite this, you should be familiar with the symptoms of dying goldfish to prevent untoward incidents from happening. Breathing disorders are the most significant sign of fish death.

Be on the lookout for rapid breathing, gasping for air, resting at the bottom of the fish tank, or skimming the tank water surface. These things might be an indicator that they are suffering from disease or that the water quality is poor.

The following are the most common causes of goldfish death:

  • Parasites like fish lice and anchor worms
  • Fungal diseases
  • Bacterial infections
  • Diseases such as a swim bladder disease
  • Internal parasites
  • Ammonia burns
  • Poor tank conditions that result in low oxygen levels

What Other Goldfish Body Discolorations Should You Look Out For?

Black spots on goldfish are probably the clearest and most obvious signs of discolorations since it contrasts heavily with the orange body. However, there are actually other types of body discolorations that goldfish owners should be familiar with. Aside from black patches, watch out for the following:

White Spots

The presence of small, white patches might mean that your goldfish is suffering from ich. It is a common parasitic disease among freshwater fish species and is caused by external parasites.

Red Spots

On the other hand, be careful if you notice red spots on your fish. This type of discoloration is associated with parasites like anchor worms and lice.

Yellow Spots

This might be harder to spot, but make sure to inspect your goldfish for small yellowish spots comparable to powder appearance.

After all, this might mean that your pet is suffering from a fish disease called velvet. It is a quick-acting disease, so sort it out right away.

Red Streaks

If you see red streaks on the fins that eventually turn white, it might be an indication that your fish is experiencing something known as tail rot or fin rot.

Pale Color

Have you noticed that the color of your fish is too washed out and pale? Be careful as this is known to be a symptom of a condition called dropsy.

This happens when there is a fluid buildup inside the tissues or body cavity of your fish. It might indicate other serious underlying diseases.

White Gills

When you notice that the gills of your fish have turned white, it is possible that your pet is suffering from a parasitic infection like flukes.

Slimy Coat

In case the coat of your fish has become slimy and milky, this might be another indicator that the creature is suffering from anchor worms or a fluke infection.

What Can I Do To Increase The Color Of The Goldfish?

Have you noticed that your goldfish has been losing its vibrancy? If this is the case, it might help if you turn to a color-enhancing feed.

There are many options that are rich in vitamins, fatty acids, and essential oils. These nutrients and minerals will help increase the vibrancy of your goldfish.

As previously mentioned, you can also introduce more lighting and brightness to the fish tank. While this might not exactly increase the vibrancy, it will stop rapid color fading at the very least.

In general, a healthy goldfish that lives in a tank with good water parameters and clean water should not have a problem.

How Can I Prevent Goldfish Disease?

It is wise to invest in prevention before anything else. Your goldfish will be much healthier if you take preventive measures.

It also tends to be cheaper and more effective than treating your pet after they contract goldfish disease.

By following these tips, you can ensure that your goldfish will be safe from illnesses:

  • Ensure that the fish tank has appropriate nitrate, temperature, and pH levels.
  • Prevent overcrowding by buying the right size for the fish.
  • Invest in a filtration system that will sort out the bioload produced by your fish.
  • Avoid overfeeding your pets. It is always good to stick to the “less is better” rule. After all, fish will keep eating as long as there is food present, but this can result in digestive problems and increase the amount of waste in the water.
  • Quarantine sick fish as soon as possible.
  • Avoid introducing snails to a fish tank with goldfish.
  • Take it upon yourself to regularly check the levels of ammonia in the aquarium.


It can indeed be worrying when you see your goldfish turn black all of a sudden. When this happens, it is best to carefully inspect the fish tank to see what might be causing the condition.

There are many possible causes behind black spots on goldfish, but there are certain reasons that are more concerning than others.

It is imperative to treat ammonia burns and parasitic infections as soon as you can since they pose a risk to the health of the fish. However, other conditions do not affect the well-being of your fish.

In case you are bothered by the loss of color, there are certain things you can do to alleviate the problem at hand. At any rate, the most important thing is not to panic and get to the root of the issue at your earliest availability.


Passionate fishkeeper. Nature lover. Creative thinker. Music junkie. Adventurer.

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