Help! I changed out my betta tank today, like I have done several times in the past 3 months since I have had them. I used tap water that has sat out for at least 3 weeks, just as I have done in the past. But now, they are both just laying on the bottom. They swim to the top for me but then slowly float back down. What went wrong?

Did they not act like this before?
What other signs of illness are they having, if any?

You said "tank", are you keeping more than one Betta in the same tank?

Is this a tank? Or Betta bowl?

The answer to these questions would help me help you better.:)