Fish slow after water change

I’m not sure if this is the right place to post this but I’m concerned.
I did a 30-40% water change today (I’ve done that once a month and all others have been fine)
As well as vacuumed the gravel for the first time.
It’s a 6.5 gallon tank with a filter and heater, water temp was the same

Since the change my Betta has been very slow and listless either hanging at the top or very bottom. The change was done with spring water treated with stress coat, which I’ve been doing because our tap water sucks.
He did get stressed during the vacuuming and I don’t know if that’s why. Just worried I did something that hurt him

That’s a lot of water to change at once. I haven’t kept fish in a while but used to do no more than 25% at a time unless it was an emergency. Do you have a water test kit?

How’s the temp?

Temp is at 75

No unfortunately I don’t.
I changed slightly more water this one (last one was like 25) because i accidentally let to much out of the vacuum

If you have a decent fish shop nearby, I’d take some water in and see if they can test it for you. If there’s no way to test, you’d just be guessing at what’s going on… it’s possible your water was more chlorinated than normal… sometimes local water supplies are at times if the water quality goes down. You might be able to check with your local water authority if they have reports available. If that’s the case, adding a little more stress coat might help if you can confirm that. I would definitely get a test kit for future water changes.


If you don’t have a water testing kit, I’m going to guess you don’t know if the tank is cycled. The cliff note version is that’s a process the filter and substrate goes through to establish enough good bacteria to “eat” the bad. It needs enough ammonia and time to develop. One Betta in a 6 gallon could take months with no water changes and each change will start the process over again if the tank didn’t build up enough ammonia to start the process.

I would remove him or the filter until you get a test and do some research on cycling a tank. I would also try some Melafix and aquarium salt in case something else is the problem.

He’s doing a little better, swimming around a bit more and happily ate his food

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