The Puffer Forum

They seem to be disintegrating, it seemed to happen very quickly, I've never seen this before. He still eats pretty well, but the rest ofthe time he just plays possum at the top of the tank, ocasionally he will jam himself under or behind the filter. I'm totally stumped

Well, that seems like fin rot... there's definitely something bad going on with him. You could try Tri-Sulfa to help with bacterial infection, which is likely what's causing the fin rot...
What's the temp in your tank? If it's not at 80F, I'd move it up to that temp.

Yeah, not a lot of people know about the side effect of Melafix and Pimafix on anabantoids like bettas. The oil in the Melafix and Pimafix gets into their labyrinth organ and prevents them from being able to properly breathe. Otherwise, it's a great product. I use it for all my other tanks with awesome success. Just don't use it on tanks with anabantoids (bettas, gouramis, etc).

I also recommend feeding peas. I take a frozen pea, thaw slightly, squeeze it to remove the shell, and then mush it up a bit. This one pea will be good for a couple feedings. And the salt thing is worth a shot too. Bump up water changes for a few days to a couple weeks to see if that helps too.