betta fish not swimming

Question
Hi there.  I have another question for you.  I have a betta male ,bought in June,and until last night he has always been active and alert.
 Last night I gave him a bite to eat before I turned in.  This morning he was at the bottom of his tank(5 gallon)and stayed there all day and is still there this evening.
He's in my bedroom where there is a/c.  I thought that perhaps he had gotton chilled so I turned on his heater and he came up briefly but soon returned to the bottom of the tank.
Is he sick or, heaven forbid, dying?  
What should I do?
Thanks for any help you can offer.
Dwight

Answer
Hi Dwight;

I'm so sorry it took so long to answer your question. I thought I already answered it Friday, but here it is!  Again, so sorry....

He probably has a failed swim bladder. Poor guy. It could have been the cooler temperature in the room, but it could also be infection or something too. The only actual treatable cause is bacterial infection. "Maracyn 2" is the only medicine that gets inside the fish to work internally. It's all a waiting game anyway though. Even if it's bacterial infection you just have to wait and see if it heals and begins working again. They often don't work again, but a fish will a failed swim bladder can live a very healthy and long life anyway. They just can't float up anymore. It helps to provide live plants to float on the top so he can rest closer to the surface or lower the water level so that he doesn't have to struggle so hard to get to the top. Keep the water temperature up to 80 or 82. It helps him heal.

I hope he gets better soon.......

At Your Service;
Chris Robbins