I have a 20 gallon (76 liters) tank with 6 goldfish - all small sized. I have had this tank for around 6 months. I do weekly 50% water changes and feed them twice a day - mostly pellets and flake food. Sometimes I give them peas.

Just around 3 weeks or so I have this one shubunkin who has started behaving different. It doesn't eat. And it just stays at one corner of the tank for the most of the time. I thought it must have had some infection so I did more water changes, but it still hasn't helped. And most importantly the other fish seem to be healthy and lively, apart from this one. It also seems to have lost some weight. I have attached an image of it.

I am unsure how I treat this fish. I am looking for some advice. It would be great if I could get any.

enter image description here

  • 2
    can you please add this information,the ph-amonia-nitrite-nitrate of your water.and here is a link on how to start cycling your tank this is important information to know fishlore.com/NitrogenCycle.htm Sep 10, 2017 at 19:33
  • @trondhansen. The asker did state the tank is 6 months old, so cycling definitely isn't the issue unless he's bleaching the tank every week.
    – Jestep
    Jan 18, 2018 at 21:22
  • To the OP, what temp do you keep the tank at and what filtration does the tank have? Can you also explain your water change procedures?
    – Jestep
    Jan 18, 2018 at 21:24
  • @Jestep this is an old question now and what is answered is to help not ony the one asking but other visitors too. Jan 19, 2018 at 6:56
  • Sorry for not updating this post. A few hours after posting this my goldfish unfortunately past away. It intestines had opened up, also it's tank mates were bullying it for a couple of days. I wonder what the cause was. Jan 19, 2018 at 6:58

1 Answer 1


Sadly I don't have a definitive answer for you, but the other fish in the tank may be bullying him. To test this I would put this fish in a separate tank and see if it's condition improves.

If not, I'd treat for a bacterial infection as I cannot see any signs of a parasitic infection such as ick based on the photo, but I'd also do so in the separate tank, as any unnecessary medications given to the other fish can harm their kidneys.

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