water change and strange beta behaviour

Question
I just changed my beta's water approximately 12 hours ago. He lives in a vase that's about 2 gallons and I've had him roughly a year. I've changed his water many times and I always use water conditioner since the water where I live tends to be less than savory.
My question is this: I'm afraid I may have used too much water conditioner... Would too much conditioner hurt him? I used the recommended amount while filling the bowl and tried to make the water as close to the same temperature as possible. About an hour after I placed him in the bowl, I noticed he was gasping and swimming to the surface a lot for air so I put in another dose of conditioner that has a stress coat in it. Since I've been home from work, he's been mostly stationary at the surface and swimming oddly, almost lop-sided, and shows little interest in food, which is very atypical for him...
Please tell me I haven't given my fish a death sentence by overdose...?

Answer
Christina,

  If he is gasping for air, that is an indication the oxygen level in the bowl is low. You can help that by adding an air stone to his vase. Better yet, putting him in a tank would be so much better. Betta's do not belong in vases nor do they belong in bowls. Never use more conditioner that is indicated on the bottle. You can do a water change. Remember to add the conditioner only to the water being added to him, not all the water. Also remember that Betta's are tropical fish and need a heater. After the water change he should be much better. If not please let me know.