How often should I be doing water change for my betta? My wife seems to think it should be done pretty often.

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    It depends strictly on the water quality. And the water quality depends a lot on the environment in the tank. Please explain what you have there. A picture (or more) might be helpful also. – virolino Jul 24 at 6:16
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    you need to give more details in your question how big is your tank,filtration,any plants,other fish in the same tank? – trond hansen Aug 7 at 17:30

The water change should help with some problems:

First, the waste of the fish itself ("poo and pee"), which will accumulate in the water.

Second, other waste, like uneaten food, dead plant parts and so on.

Third, the new water brings new oxygen, important for the fish to breathe easily.

The impact of these three points is different with every setting of your tank. In a big tank, it takes more time to reach the toxic concentration of waste or to breathe all oxygen away than in a smaller. If you have some plants in the tank they would influence it positively, because with enough light they will use waste as nutrition to grow and produce oxygen. If you use additional equipment like a pump with a filtration system, then the waste will be taken out, and if you let the water from the pump drop into your tank this will bring new oxygen into it.

In any case, you should regularly do water tests, because it could happen at any time that there are high levels of waste that the plants or the filtration pump could not manage. (For example, if the filtration material in the pump is too dirty and needs change/cleaning.)

Long to short: If your betta lives in a glass of water, yes! You need to change the water very often.

(I have to assume the worst case, until you give more detail.)

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Assuming you have a proper tank for him (cycled, with heater, filter and adequate size), changing 20 or 30% every week or at least once every 2 weeks is best.

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    please expand this answer,what is a proper tank?what is cycling a tank?what is an adequate size for a filter?what amount of water to change every week?.all this information is missing from your answer. – trond hansen Aug 7 at 17:38
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    sadly the most betta owner are told to let their betta live in a tank with the size between a milk bottle and a water bin... without cycle pump, without heater and all the other stuff one uses for a proper aquarium – Allerleirauh Aug 8 at 16:51
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    Not sure why this answer was downvoted when the other one is completely inaccurate from every angle except change water a lot if they live in a small glass. And obviously, there is no universal "proper tank size" which I'm assuming is why Trond downvoted. – Jestep Aug 17 at 20:09
  • Hi @Jestep I recall this answer once being in a low-quality queue where it was probably automatically placed due to extremely short length. But I am not one of the people who voted it down - I think it doesn't deserve -2 score, after all it is technically correct and features well formed English, just is extremely short and I guess it was a dealbreaker for people who voted down. – lila Aug 19 at 1:50

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