Why do goldfish change color?

Have you looked at your goldfish recently and thought that it looked a different color?

Have you compared old photos of your goldfish to now and noticed that your fish’s color used to be brighter?

You may even have noticed your goldfish gradually turning white!

Don’t worry, you’re not going crazy! It’s actually perfectly normal for goldfish to change color over the course of their lives.

(Ok, maybe not quite as much as in the picture! If your goldfish goes that color then consult a vet!) 

Read on to find out why goldfish change color…

Has your goldfish changed color?

The main reasons that your goldfish may have changed color are:

  • Maturing to adulthood – goldfish are actually brown when they’re born, and develop their adult color later!
  • Diet – some goldfish foods bring out color in goldfish more than others
  • Amount of sunlight – goldfish in a pond or an aquarium that gets some sunlight will be more brightly colored than goldfish kept in darker conditions
  • Poor water quality – you should get a test kit that measures ammonia pH, nitrite and nitrate. Make sure that you’re using a suitable aquarium filter and doing enough water changes, as poor quality water can make goldfish color fade (and is bad for your fish’s health of course!)
  • Illness or disease – again, check your water quality and look for other symptoms of disease
  • Genetics – some goldfish change color as they age, simply because goldfish can live a very long time and that’s what their genes program them to do!

If your water quality is good and your fish is getting enough sunlight, then don’t worry about any gradual change in your goldfish’s color. Your fish could be changing color for any of the above reasons, or perhaps other reasons, and it’s almost certainly nothing to worry about.

However, if you notice your fish change color very suddenly, or only in localized areas of their body (small white spots for example) then you should consult a vet or search for the symptoms online. It’s possible that your fish could have a disease such as “Ich” (also known as “white spot disease“).

6 thoughts on “Why do goldfish change color?”

  1. Hello,
    I’ve noticed reddish spots on my common goldfish’s tail. Can you tell me what this may be? Ammonia levels and ph are In a healthy zone.
    Thank you!

    Reply
    • Hi Jessica. Sorry to hear this about your fish! It could be a bacterial infection. Does it look like this?

      When you say “ammonia is in a healthy zone” do you mean zero? We would suggest that ammonia should be zero in a well cycled tank and anything above that – even low levels – would be a concern and could either harm your fish or let bacterial infection take hold.

      Reply
  2. Hi,
    I have 2 golfishes. But only one of them changes its color to black and only in specific areas. I just bought them 3 days ago. The other one doesn’t change color at all. Is it something to worry about?

    Reply
    • Hi Shifa, thanks for your comment,
      You should do a water test to see if there is anything wrong with the tank which could cause any problems, if this is fine, and the goldfish are eating, swimming around and otherwise look healthy, it is probably nothing to worry about, goldfish often change colour throughout their lives, and actually most goldfish start out completely black when first hatched.
      If there is something wrong with the water, perform a water change, or if you do suspect a disease, here is some help with identifying it: https://thegoldfishtank.com/goldfish-info/diseases/goldfish-fungus-types-of-fungus-causes-and-treatments/
      hope this helps.

      Reply
  3. Hi,

    My goldfish was a dirty silver/gold with black patches on it back.
    We’ve gone away for 4 days and the fish is now completely a bright golden colour with a slight black on its fin.
    My mum has been taking care of them whilst we were away.
    Is this possible or is it a new fish?

    Reply
    • Hi Kerri, thanks for your comment,

      Yes it is entirely possible for goldfish to change colour, this is especially true with younger fish less than 4″ long.

      However, this change is normally gradual, and usually takes weeks to change colour completely.
      The fish may also just be washed out from stress, you may need to do a water change.
      Give it a day or two and test the water to make sure it is okay, you might find it changes back to its original colour, after it has settled down.

      Look for other features you may recognize in your fish, like the shape of the fins, size and behaviour, if it is completely different from what you remember then your suspicion may be correct.
      perhaps an interrogation is in order!

      Reply

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