Goldfish Turning Black? Top 4 Causes & Ways To Get Better

You see your goldfish turning black and you are worried. But should you be?

What does it mean when your goldfish turns black? And what to do with it?

Let’s find out in our big goldfish blackening guide!

In this article, we uncover the top 4 reasons why goldfish turn black and – for each possible reason – explain what you need to do to keep your fish safe and healthy.

Why is my goldfish turning black?

It is not uncommon for goldfish owners to notice that their goldfish are turning black.

Black spots may appear on the head, scales, tail, or you may notice your goldfish’s fins turning black.

Blackening of a goldfish can be a big problem, so you should always find out why this is happening.

Suddenly appearing black dots on goldfish should not be cause for concern, but may be a sign of a serious problem. Therefore, it is important to find out the reasons why your goldfish turn black as soon as possible and begin treatment if necessary.

4 reasons why goldfish turn black

  1. Ammonia burns
  2. Healing from trauma
  3. Natural color changes
  4. black spot disease

Of these causes, ammonia burn is the most common.

Unfortunately, ammonia burns are also extremely dangerous and often fatal. That’s why it’s so important to act quickly to understand the reasons why your goldfish is turning black.

Below, we will look at each of these four causes in turn, including how to determine which is causing your goldfish to turn black and what you should do about it.

Goldfish turn black due to ammonia burns

Ammonia is a chemical found in your fish’s feces. This is very dangerous for goldfish and can burn the fish all over its body.

When a goldfish suffers from an ammonia burn, its body tries to heal itself. This causes black spots on goldfish in the same way that a burn on human skin can leave a scar.

Orange goldfish with black ammonia burn spots.
Goldfish with ammonia burn

Therefore, to some extent, seeing your goldfish turn black is a good sign. This means that the ammonia burn is healing!

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However, if your fish has been scalded by ammonia once, you need to take steps to ensure it doesn’t happen again.

How to know if ammonia burn is causing your goldfish to turn black

The first step in deciding if ammonia burn is causing your goldfish to turn black is to do an ammonia test.

You should also check for nitrites and nitrates to make sure your tank is properly cycled.

High nitrite levels can be a confirmation of ammonia burn, as they may indicate that the cycle is not working properly in your tank and your fish may have recently experienced high levels of ammonia. Nitrites themselves are also dangerous for goldfish.

We also recommend checking the size of your tank and making sure it is suitable for the number and size of fish you are keeping.

If your tank is too small or overcrowded, you will likely experience ammonia surges that will cause an ammonia burn.

How to prevent ammonia burn

If your tank is well set up (including the correct cycle) and you change the water regularly, then your tank should be free of ammonia. Any ammonia excreted by your fish is quickly removed or converted to nitrite by bacteria.

However, if your tank is not cycling, has too many fish, or is too small, ammonia levels will start to rise.

Unfortunately, it doesn’t take much ammonia to start burning the gills, scales, and fins of your fish.

A goldfish living in water containing ammonia is stressed, has breathing problems, and most likely dies fairly quickly.

So the way to prevent ammonia burning is to have a large enough tank, keep a reasonable number of fish, make sure your tank is on the right cycle, and do regular partial water changes.

Never add untreated tap water to the aquarium (use Seachem Prime first) and never wash the filter sponges in tap water. This can kill the “good bacteria” formed during the cycling process and effectively disperse your tank.

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Finally, check the ammonia, nitrite and nitrate levels regularly to always have a good idea of ​​the condition of the water in the aquarium.

Goldfish turned black due to injuries

When a goldfish is injured, its body tries to heal itself just like the human body.

In humans, we see scabs and scar tissue at the site of injury, and we know that this is a sign of healing.

In goldfish, this healing tissue is black. So black spots on your goldfish could be a sign that your goldfish has been hurt but is getting better.

If you know that your goldfish has recently been injured and the black mark is in the same place as the injury, then this is almost certainly the reason why they turn black.

If you are not aware of any injury, but think that the goldfish may have been injured (for example, by a tankmate, in a vehicle, or by some object in the tank), you should monitor the fish closely and remove the risk of injury if any. possibly.

If the wound heals on its own—and the blackened part of the goldfish suggests it does! – then there is usually no need to intervene and you can simply let the injury continue to heal naturally.

Can a goldfish be black or naturally black?

It is quite natural for your goldfish to develop black dots, streaks or spots.

They may be born with black patterns, or these patterns may develop later in life along with other colors and patterns.

The coloration of goldfish usually changes throughout life, at least to some extent, and some of this change, including black markings, is not necessarily a cause for concern.

There are also some types of goldfish that are supposed to be black or part black. These include the black moor and other calico-patterned types such as the shubunkin.

It’s usually easy to tell when your goldfish turns black, it’s just part of the natural color change. In these cases, the changes are usually gradual, the blackheads do not look painful, and there is no change in the behavior of the goldfish.

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However, if you notice that your goldfish has suddenly turned black, black markings seem to be related to injury, there are also red markings or other physical problems such as worn fins, or your goldfish starts acting differently, then this is unlikely to be natural. .

When blackheads appear suddenly or along with other physical or behavioral changes, they are much more likely to be caused by an ammonia burn or injury.

Black Spot Disease: Why Does My Goldfish Have Black Spots?

As explained above, the most common cause of black spots, black spots or black spots on goldfish is the healing of burns or injuries with ammonia.

Black spots are not usually a sign of illness, illness, or infection.

However, one possibility is worth mentioning.

There is a disease known as “black spot disease” which is a parasitic infection that causes black spots to appear on fish.

But before you jump to the conclusion that your fish has black spot and not ammonia burn, you should know that black spot is rare. (Unlike ammonia problems, which are very common!)

Your goldfish can only get black spot if they are kept in an aquarium with snails or a pond. This is because the life cycle of the parasite involves transmission through bird droppings, entry into the water where it infects snails, and then proceeds to infect fish.

The infected fish are then eaten by other birds and the cycle continues.

Because this happens so rarely, we strongly recommend that you consider other options before treating goldfish for black spot. However, if you are convinced that this is the cause of your goldfish turning black, then a treatment such as PraziPro may I help.

Featured image via Reddit.

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