Beta fish ill

Question
My Beta, Buddy, has over the last week began to sink to the bottom of his bowl. He lies on his side. Occasionally, he gets a spurt of energy and swims around at a rapid rate and then slowly sinks. We enetered your question area yesterday. We got the Stree Coat and we put a heating pad under the bowl. There is a thermometer on the outside of the bowl and we've got the temp between 80 -82 degrees F. We took some frozen peas from a frozen tuna casserole and removed the husk and mashed it into the water.
He made it through the night, checking the water temp each 2 hrs. What else can we do. He's about 1 yr old. He's a BIG beta.  
The bowl is approx. 1 gallon. The water has been changed weekly with tap water that is familiar to him. Howevre we changaed all of it, not 30%. We don't know the pH  

Answer
Hi Karen;

Poor guy. He probably has a failed swim bladder. The swim bladder is an organ that controls buoyancy. When a fish wants to go up in the water, the swim bladder fills with blood gasses. If they want to go down, the swim bladder gasses dissipate back to the blood. If it fails it can no longer hold gasses. Failure can happen from low temperature, shock or internal infection. Some bettas heal just fine and recover the use of their swim bladder over time. Most don't though, but they live long otherwise healthy lives anyway. Keeping the water clean and higher in temperature is the best you can do for him. It really is a 'waiting game' with this condition. It is unlikely he is in any pain or suffering. He may get frustrated at having to struggle to get to the top for a gulp of air every so often. You can lower the water level to help him reserve energy. Just change his water more often since waste toxins will be more concentrated with less water.

Hope he has a full and speedy recovery....

At Your Service;
Chris Robbins