Goldfish randomly keep dying
Long story short we've had fancy goldfish for over 2 years now... We started out with 2 goldfish and still have one of the OGs to this day and he looks happy and healthy but the other OG one died after 1 year so then we got another which died after 4 Months in the tank and then ANOTHER one that's just died after 2 months in the tank but the original fish is still fine and swims and eats so i'm at a loss with what's happening?
Tank water is cycled every couple weeks (50L Tank) new filters periodically swapped in and out (not all at once as to keep the good bacteria cycling round if that's good or not please let me know) nitrate levels are measured and safe every week or two and general cleaning and other maintenance done at least once a month.
There's plenty of real plants in there with an air stone for good oxygen levels etc.
I honestly don't get it as before we went to bed last night both of the fish were swimming around and energetic but then this morning the one of them is just lying on a leaf.
I would really appreciate it if all critiques and advise is constructive as me and my partner inherited these fish as we never actually wanted them but we thought it would be best to learn and take care of them as flushing them down the loo just felt wrong.
Any pointers would be greatly appreciated here so thanks for any comments :)
Posted Jan 27, 2026, 11:41 AM UTC