Why is My Goldfish Turning Black? (Causes and Cure)

goldfish

If you are an avid fish keeper, then it is likely that your goldfish must have had black spots at some point. Your goldfish is just like your other pets, they get sick too, and they experience normal changes in their bodies as well.

“Why is my goldfish turning black?” Black spots start to develop on your goldfish either due to a fluctuation in tank conditions or even due to other reasons which we would be looking at in this article.

Goldfish Turning Black Causes

To fully understand the reason why your goldfish might be turning black, reflect on these questions.

What is the ancestry of my goldfish?

First, you have to make sure that your goldfish is not a mixed breed, mixed breeds are gotten from cross-breeding goldfish with other compatible species such as koi fish.

So it might be important that you are sure that your goldfish is actually a purebred goldfish and not a mixed breed that might start displaying a few colors that might have been present in one of its parent.

Was the onset sudden or gradual?

Your goldfish might just be one of the species known as the Panda moor goldfish that starts to develop black spots on their white bodies as they begin to mature.

If the onset is gradual, then it might be due to the normal process of maturing, whereas if the appearance of the black spots is sudden, it means that there is an underlying cause which you might have to investigate.

Is my tank a new one?

Cycling is an organic filtering system that is essentially carried out by bacteria. It involves the conversion of ammonia- which is gotten from the degradation of your fish waste product into nitrite, then other bacteria further degrade the nitrite into nitrate, this helps to prevent the buildup of ammonia in your tank.

If your tank is a new tank, the cycling system might not be fully developed yet, so your goldfish might be suffering from ammonia burns which might have been gotten from a buildup of ammonia.

What is the size of your tank?

If your tank size is less than 20 gallons for one goldfish or 50 gallons for 5 goldfishes, then it is possible that your goldfish is not getting enough swimming space, in addition to the buildup of toxins from a small tank.

Black spots might be one of the outward symptoms that your goldfish is stressed from unfavorable living conditions such as a small tank.

Are there black decorations in my tank?

Naturally, the fins and some parts of your goldfish contains melanin which is responsible for dark pigments, keeping your goldfish in a tank with a dark background or with dark decorations might stimulate the production of more melanin in your fish fins or any part of its body, resulting in the dark spots that are visible on the body of your goldfish.

What are the levels of ammonia in my tank?

Every fish enthusiast should be familiar with the harmful effects of ammonia on a fish tank. Ammonia poisoning might result in the visible display of black spots, which might be good or the absence of black spots, which is bad.

Let’s see how this is possible. Usually, scars are formed during the process of wound healing, right? So, visible black spots on the surface of your goldfish might mean that your goldfish has suffered a previous ammonia burn and is trying to heal from it.

However, the absence of black spots but with other symptoms which we would be discussing later in this article might mean that your goldfish has suffered ammonia burns and is possibly still suffering from them and has not had enough time to heal from this. So you see the absence of the black spots might be bad?

Goldfish Turning Black

Are there fish snails in my tank?

If there are fish snails in your tank, this is probably another reason why your goldfish has dark spots. This is because; aquatic snails serve as a host for a dark-colored parasitic flatworm that completes a part of its life cycle in freshwater fishes, like your goldfish!

These parasites wreak their havoc in two ways, First, they dig deep into the skin of your goldfish and try to lay their eggs there, this turns that area of your goldfish black.

The other way is through an immune response of your fish to them, your goldfish starts to form cysts as a form of protective measure on the areas they have burrowed into, which might be another reason for the black spots.

Could my fish be possibly injured?

Just like any other animal, your goldfish bleeds, so if it is injured decoration or any other pointy object in your tank, black spots might be as a result of the collection of blood from a hemorrhage that might be due to pointy objects in your tank.

Is my filter working effectively?

Goldfishes are known to be producers of large quantities of bioload which may be degraded and an ineffective filter might cause their accumulation in your tank.

If your tank is not equipped with a functional filter required for a tank of its size, this might cause an accumulation of ammonia in your tank and might be the reason for the black spots on your goldfish.

How often do I do a water change?

Apart from having a functional filter, without adequate water changes of about 3% of the water in your tank every two weeks, ammonia can accumulate in your tank and may cause ammonia burns on the body of your goldfish.

If you answered yes to any of these questions, you should now know why your goldfish might be turning black.

Do goldfish change color to black?

Definitely! It is possible for your goldfish to change its color to black. Most times, your goldfish changes from other colors to black as a consequence of aging.

Although, in the initial two years of a goldfish life, some of them start out black in color and subsequently begins to turn red or orange, if this doesn’t happen that means your goldfish might just be the highly prized Black Moor goldfish.

If the black spots start to develop gradually, it might be due to a normal process in your fish: whereas, if the appearance of black spot is sudden, this might be a source o worry especially when you notice other symptoms such as loss of appetite, rapid breaths, or torn fins.

How to help your Goldfish that has turned black (Cure)

The course of treating or preventing black spots in your goldfish depends on your answers regarding the causes of black spot in goldfish.

If your tank is a new tank, cycle your tank first

Cycling involves colonizing your new tank with bacteria that would help to degrade ammonia into a la less toxic product like nitrate. It can be done in three ways.

The first method is with the use of hardy fishes- that survive in harsh living conditions like guppies and minnow, then you allow them to produce sufficient ammonia, an increase in the levels of ammonia produced would result in the growth of more ammonia degrading bacteria in your tank.

But this method results in the death of these fishes, so it might not be recommended. However, the second method is more preferable and less time consuming is done by adding synthetic ammonia to your tank to promote the growth of these bacteria.

The third method involves adding an object such as decorations or rocks,  from an already established aquarium to introduce these bacteria to your fish tank.

If your tank is too small, get a bigger tank

A bigger tank such as a 50-gallon tank if you have 5 goldfishes might be advisable because it allows your fishes to swim freely and prevents the accumulation of toxic waste that is produced by these goldfishes.

If there are any black decorations in your tank, get lighter colored ones

A lighter colored rock or decoration is not likely to cause the production of more melanin in your goldfish.

If you suspect high levels of ammonia in your tank, make sure that you are not over-feeding your fishes as this could also result in the production of ammonia.

You would also be required to get a test kit to measure the levels of ammonia, nitrite, and nitrate in your tank every day.

For an ideal tank environment, the levels of ammonia in your tank should be 0 ppm, this would help to prevent ammonia burns that might cause the black spots on your goldfish.

If there are fish snails in your tank, you might be required to remove them,

They might be a host of the parasite that is affecting your goldfish. You can also use tweezers to carefully extricate the parasites from your goldfish.

If there are any sharp decorations in your tank, remove them

As you know, pointy objects might harm your goldfish, so you would want to make sure your tank contains no sharp objects that might harm them.

If the filter in your tank is not working properly, get a more effective filter.

In addition to cycling, a good water filter is required to maintain an optimum living environment for your goldfish to thrive in.

If you do not routinely change the water in your tank, start doing that every 2 weeks

Regular water changes help to remove debris, organic waste product and uneaten foods in your tank that might accumulate and result in the production of ammonia which might harm your goldfish and cause them to display black spots.

Overall, to prevent the appearance of black spots, which might be caused by unfavorable living conditions in your tank, you have to make sure that you maintain a high water quality in your tank that involves daily monitoring of the temperature, ph, and ammonia levels.

If you have done all this, and your fish displays symptoms, it is advisable to take your goldfish to a veterinarian or a goldfish specialist.

goldfish turning black cure

Will the black spots on my goldfish go away?

You might be worried that the black spots might become permanent, this is not the case at all. Think of the black spots as the healing scab that is formed during the process of healing.

As far as you improve the unfavorable conditions in your tank and make your tank more comfortable for your goldfish to thrive in by maintaining optimum temperature, ph, water quality, a tank devoid of ammonia, these healing scars should eventually fade away as part of the final process of healing.

How do you know when your goldfish is dying?

This is one of those questions that if answered might help to prevent the deaths of many goldfish in fish aquariums. These are the outward symptoms that might be displayed by a dying goldfish.

But first, what are the things that could result in the death of your goldfish

  1. Unfavorable tank conditions that might cause low levels of oxygen
  2. Diseases such as swim bladder disease
  3. Ammonia burns
  4. Bacterial Infections
  5. Internal parasites
  6. Fungal diseases
  7. Parasites like fish lice and anchor worms

If your goldfish is not getting enough air due to inadequate levels of oxygen in their tank, the symptoms that might be displayed include:

  • Rapid breathing
  • Swimming towards at the bottom of the tank
  • Swimming with mouth opened

The symptoms of Swim bladder disease which might cause the death of your goldfish include

Symptoms of a fungal infection might include:

  • Rotting fins
  • Clamped fins

Ammonia poisoning: Ammonia attacks fish gills first, so the first symptom your goldfish might present with, is red gills

Others are:

  • Rapid breathing.
  • Dullness in color

The symptom of a parasitic infection such as anchor worm or fish lice infestation include

  • Continuous flicking
  • Scratching against hard surfaces on the tank
  • Loss of appetite
  • Weight loss
  • The dullness of your goldfish

Make sure to quarantine any goldfish that might start to display any of these symptoms, so that you can be able to monitor it and effectively treat it, this would also help you to prevent the spread of the disease across your fish tank in the case of the ta transmittable disease.

Then take your sick goldfish to a goldfish specialist or a veterinarian that can properly diagnose and treat your goldfish.

Why is my fantail goldfish turning black?

The fantail goldfish is one of the most popular dishes that are kept in fish tanks. They possess very vibrant colors of red, white, orange and gold. Contrary to how delicate they might look, fantail goldfish are hardy fishes.

Meaning that they can survive under certain conditions that other fishes might not. However, the optimum temperature they require is between 70 and 80 degrees Fahrenheit.

The optimum ph required for them to thrive is between 7.2 to 7.6. Their average length about 6 to 8 inches, and they can live for about 4 to 10 years, some fantail goldfish have been recorded to live for as long as 15 years!

Your fantail naturally has no black spots, however, if it is stressed due to some reasons, it might begin to display black spots.

These reasons include:

Poor water quality in the tank- Although they are hardy dishes and can still thrive in some head conditions, however, continuous exposure to these conditions might stress them and they may start to develop black spots.

Small sized tank: Ideally, one fantail goldfish requires at least a tank size of 10 gallons or more if you can afford it and you have enough space, so keeping about 5 fantail goldfish would require about 50 gallons. Keeping too many fantail gold fishes in one tank might stress them and result in the display of black spot.

Ammonia burns. Inadequate filtering in your tank can result in the accumulation of ammonia which is gotten from the degradation of your goldfish’s waste product, this accumulation can result in the production of ammonia burns on the body of your fantail goldfish.

Tank ph: Monitor the levels of ph in your tank daily to avoid fluctuations in Ph that might eventually stress your fantail goldfish.

To correct this,  make sure that the living conditions in your tank are made favorable for your goldfish.

  • Do a regular water change.
  • Monitor ammonia levels.
  • Check ph and temperature levels regularly

Although seeing black spots on your goldfish might be a source of worry. You really shouldn’t be, except when you start noticing the other symptoms which we have discussed.

It would be good for your goldfish if you seek the help of a goldfish specialist at this point, because any delay might result in the death of your precious goldfish, and you would not want this to happen, right?

It is better to avoid this by making sure that your goldfish do not become stressed and start to display black spots, it is safer to prevent this by making sure that the environment in their tank is favorable enough for them.

Saurabh Kumar

I am a passionate fish keeper, with years of experience. You will find some really useful tips and information on this blog about Freshwater Aquariums.

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