Help!!! Somethings wrong with my Betta!

Question
2 gallon tank, one female betta fish (age unknown), no filtration system but does have a heater, water changes about every two weeks (yup, i do use aquarium salt), tank's be in operation for about 6 months.

I just changed her water today, it was probably over 2 weeks because I had to wait to get the water (we get it from our rental because we don't have to adjust the pH that way).  I let it sit out for over 24 hours to get the chlorine out like I always do.  But when I got her back in the tank, she was acting lathargic and just kinda sitting there.

When I checked her tonight, she was just floating at the top of her tank, not really breathing with her gills too much, but taking glups of air every once in a while.  She would swim to the bottom, and then just float back up w/o any resisance.  Fins are crossed and clamped against her body most of the time.  Her color is pretty faded too.  I had noticed that before I changed the water this morning she was not as interested in her food as she usually is.  She's really scaring me, I've never seen her act like this, not even when I first brought her home.

I did take her out of that water and into some other water from a different "batch" in a smaller container, and she seemed to be doing a bit better there.

From reading stuff online, i'm guessing it's either something in the water that bothered her for some reason, or swim bladder disease (which i was guessing because of the way she was floating) I could be the culprit here, I have a feeling I was feeding her too much and that could be the problem.  

Answer
Hello!

There are 3 things that you are doing very wrong.

1) Salt. Salt is BAD! Do not let any employee tell you it is good. Salt is good as a cure for disease, so people assume that it can also prevent disease. This is not true. If you take medicine when you are not sick, it can make you sick. So slowly wean off the salt. Use less each time until there is no salt at all.

2) Water changes. Should be at least once a week. About 80% for a betta.

3) Use a water conditioner! Letting water sit does not evaporate chlorine. Cities put chloramine in the water so the chlorine will NOT evaporate. You must use a water conditioner like Seachem's Prime or Aquasafe to get the chlorine out. These things are very cheap and a $5 container should last you forever. And make sure the water you are changing is the same temp as the water your fish is in...which should be about 72-77 in case you were wondering.

If it is swim bladder, it will have been caused by these things.