Why do goldfish turn white?

This post was written by a guest author and edited for style/readability by our editor.

A few months into having my first goldfish, I noticed she was turning white. Being a new fish owner, of course I was alarmed. What had I done wrong?

Instead of feeling the urge to give up, I instead did extensive research on the subject in order to learn as much as I could about this occurrence.

So, why do goldfish turn white? There are a number of possible causes:

  • Not enough light
  • Natural color change because of aging
  • Too much light
  • Change in water temperature
  • Dangerously low dissolved oxygen levels in your water
  • Ammonia poisoning
  • Poor water quality

Let’s talk about the different causes and how you can find out which one applies to your goldfish.

What Are the Most Common Reasons Goldfish Turn White?

Luckily, a white goldfish isn’t always a bad thing.  The most common reasons why your goldfish might have turned white actually aren’t all that dangerous to it.

A Natural Shift in Your Goldfish’s Color

The most common reason your goldfish might be turning white is genetics.  Due to selective breeding, white goldfish are just as commonplace as golden and yellow ones.

You might think that just because your goldfish is a bright orange when you get it, that’s the color it will stay.

You’d be wrong, however.  Here’s why:

It’s not uncommon for a young goldfish that has a lot of color to turn silver or white as it gets older.

As your goldfish matures, it can change color based on its genetics. These changes are most prevalent within the first or second year of its life. It is difficult to predict when or if this will happen to any goldfish in particular when you’re purchasing it.  (If you can confirm its parents’ colors, however, you can get an idea of the likelihood it will change colors as well.) 

The bottom line?

If your goldfish slowly loses its color and turns white or silver – and you have verified that your water quality or light level is not the problem – it’s most likely a natural process.  (And thus completely harmless.)

Let’s talk about light levels next.

Shedding Light on the Issue

A very common reason why your goldfish might be turning white is because you have it in the wrong level of light.

This could be either too little light (most common) or too much light (if you have it in direct sun).

In either case, it most likely won’t turn completely white.  (It will be more of a pale color that just looks white compared to a proper goldfish.)

If you keep your fish in the dark (or in very low light), it’s much more likely to lose pigment compared to one that is kept under proper aquarium lighting or in indirect sunlight.

This isn’t an open invitation to go and move your goldfish out into full sun, however.

Too much light can cause the same problem.  (In addition to the other issues that full sun can cause – temperature swings, algae, etc.)

Temperature Change

A change in the temperature of an aquarium can cause a goldfish to lose its color. The recommended temperature of the environment is in between the range of 65 to 75 degrees Fahrenheit, or 18 to 24 degrees Celsius. Aside from this allowing the goldfish to keep its original pigment, the temperature range is also the healthiest for it to live in.

Can Color Change Be Caused by Negative Factors?

Color changes aren’t all caused by (relatively) harmless situations.  Sometimes, it can be the sign of something dangerously wrong.  Below, we’ll cover some of these situations and how to recognize them.

Here are a number of things that can stress your goldfish – causing them to turn pale or white.

Suffocating Your Fish

One of the reasons your goldfish might become pale is because the oxygen levels in your aquarium are too low.

This can be caused by a number of things, such as:

  • Bad Aeration
  • Overcrowding
  • Water temperature is too high
  • You aren’t giving your planted aquarium enough light
  • And other water quality issues

Let’s break this down in more detail.

Most of the gas exchange (getting rid of CO2 and bringing in oxygen) that happens in your water happens at the surface.

If the top of your aquarium (or pond) isn’t being agitated enough, it can severely cut down on the amount of oxygen present in your water.

This can be fixed by either an air stone or by adjusting the flow rate and output direction on your pump so that it agitates the top of the water.

Water that is too warm is also able to hold less oxygen.  Combined with the fact that goldfish are cold water fish, this can be a one-two punch that can stress out your goldfish.

There are other possible reasons for low oxygen level:

If you have too many fish for the size of your aquarium or pond, there might not be enough oxygen in the water to support all of them.

In this case, you’d notice the larger fish having problems first.  (You’d also probably notice too much ammonia in the water.)

Plants can also contribute to this issue.  (You might be a bit confused now, because don’t plants produce oxygen?)

Yes.  They do normally produce oxygen.

If you’re not giving them enough light, however, it’s possible that they might actually be removing oxygen from the water.

Not to mention the reduction in water quality from any dead plant parts that aren’t cleaned out of the water.

Finally, if you’re using certain chemicals to treat parasites or regulate water in a goldfish’s tank, they might affect the ability of the water to retain oxygen (if used excessively).

If low oxygen is the issue, you’ll probably notice some other symptoms:

  • Lethargy
  • Gasping for air

Low dissolved oxygen is definitely one contributing factor to bad water quality.  It’s not the only one, however.

Ammonia Poisoning

Excess ammonia (or KH) is another potential reason why your goldfish might be turning white.

This is especially true if your goldfish has white patches (or black patches – which happens as the ammonia burns start to heal).

To diagnose this, check your ammonia levels and your KH.  Ammonia should be 0 ppm, and KH should be between 100-140 ppm.

If you have too much ammonia, stop feeding your goldfish and do a water change to help reduce the amount of ammonia.  (This should be a temporary measure until you can treat the cause.  Look into moving your fish into a bigger tank and/or getting a filter that has more surface area – and thus more ability to remove ammonia from the water.)

Disease

If your goldfish is turning white in spots, this is a sign that he is sick.

The most likely cause of this is the ich parasite.

Luckily, this can be easily treated – if you catch it in time.  (If not treated promptly, ich can kill your goldfish in a few weeks’ time.)

The best way to treat ich is a dedicated product for treating it – such as API Super Ich or Ich-X.

WARNING: When using commercial medications, be careful what you are putting in your aquarium.  If you have inverts, putting a copper based medication in your tank will kill your inverts.  Using more than the recommended amount may also kill your fish.

Another way that people have reported successfully treating ich is by mixing 2-3 tsp of aquarium salt per gallon of fish tank into a bucket and slowly adding that into your aquarium.

This increased salinity is supposed to be able to kill the parasite without harming your fish.  (If you have fish besides goldfish in the tank as well, do your research to make sure they can handle that level of salinity – should be around 4.5 parts per thousand, if I haven’t screwed up my calculation.)

For more information on ich, check out this video:

Related Questions

Are there Ways to Turn the Goldfish Back to its Original Color? If your goldfish has changed color because of genetics, you likely will not be able to change its color back.  If the color change is the result of a disease or poor water quality, fixing the issue should result in the fish gaining its original color back.  Feeding a food designed to enhance goldfish color may also help.

Why is my goldfish turning black? If your goldfish is turning black, it may be a sign that the ammonia in your water is too high, and the black is the result of ammonia burns.  This is especially true if your goldfish is turning black in patches.  Test your water and make sure ammonia and nitrite are both at 0 parts per million.