One of my goldfish, which I've had for 3 months, suddenly got a white patch on the top and a white spot on its left side (the yellow-black one in the picture). I just noticed it today, but I'm sure it wasn't there yesterday, so it happened very quickly.

enter image description here enter image description here I just moved my fish to a new, larger, 20 gallon (76 liters) tank 10 days ago, and added a Seachem Flourite substrate, but other than that everything is still the same.

Any help is appreciated, thanks.

UPDATE: the white film on the fish seems to be spreading, I see it on its head, gills, and tailfin enter image description here

I also noticed brown spotting on its fin and from researching online apparently it might be from ammonia but I've been doing 10% water changes almost daily, and none of the other fish appear to be affected, anyway I did a 50% change today since I didn't have any water testing strips lefts just to be safe.

enter image description here

but the thing is you can only see it under a bright light, when it's not directly under the LEDs you can barely see it enter image description here enter image description here enter image description here

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    welcome to pets.SE, which of the two orange/white fish in the picture do you speak about? Nov 18, 2020 at 4:38
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    @Allerleirauh I'm not question author, but I think the description matches that yellow-black fish in the right that is lined up with a heater.
    – lila
    Nov 18, 2020 at 10:29
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    @Allerleirauh it is the yellow-black one as lila mentioned. I think it's spreading too, I think I see a white patch on its left gill today. I will update my post and try to get better pictures, but they're just so tiny and keep moving quickly. Nov 18, 2020 at 18:05

1 Answer 1


Have you added any new soils or plants or rocks or fish? That is how white spot disease spreads. It is highly contagious so I highly recommended to get medicine as fast as you can. If left too long, it will spread and may possibly kill your goldfish. Turning up the temperature will help.

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