I have two goldfish and have kept them in a fish bowl for now. As I do not have a water filter in there, should I change the water daily in the bowl? It does seem a bit dirty after a day, but I don't know if it is in fact dirtier than it should be.

Of course, as many other answers suggests, I will only change only 40-50% water at a time.

3 Answers 3


It is in fact very harmful to put fish into an aquarium on the same day you've set up the aquarium. An aquarium needs to cycle before you can add any fish to it. More information about that here

Also, as mentioned before, a bowl is too small for goldfish, in fact it is too small for any type of fish.
If you are serious about keeping goldfish, have a look at this article 12 Mistakes goldfish keepers make
But I guess this information is coming a bit too late now...

So, if possible, I would try to take the fish back to the shop where you bought them.
Then do some research about keeping fish or ask questions here on stackexchange.

If they don't want to take them back, then it is indeed required that you do a daily partial water change now, otherwise the levels of nitrite and ammonia will raise to high, and will potentially kill your fish.


Short answer:

A bowl is too small for goldfish. They need at least a 21 gallon / 79 liters (80 cm length) tank with a good filter because they produce too many organic material; more than most of fish.

While you do not buy a new tank, it would be good idea to change 40% of the water everyday. You should keep the water alkaline. Feces and urine will turn the water acidic. Do not forget to use anti-chlorine on the new water and be careful with the new water temperature; it would kill the fish if the temperature changes too quickly.


The other answers explain properly why the bowl is not suitable for the goldfish.

If you want to go on with this setup, then there is a small hack you can try. It is kind of expensive, and I do not know if it will actually solve the problems (I never had goldfish).

Use an external filter, and "connect" it to the bowl with the 2 mandatory tubes. This solution has a few advantages:

  • mechanical filtration;
  • additional (optional) filtering, depending on the model (from active carbon to UV light);
  • creating colonies of beneficial micro-organisms inside the filtering medium in the filter;
  • no space is used inside the bowl by the filter (except the 2 tubes).

It does seem a bit dirty after a day

That is a sure sign that mechanical filtration is needed. You can achieve that with a filter, or with water changes, as you already know.

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