The Puffer Forum

That's what I thought as well.

I was reading in another forum that feeding every 3 days or so is better than more frequently. I inadvertently fed him two days in a row. Might this have precipitated his downfall?

A healthy fish would not have been adversely affected by meals two days in a row. These fish are opportunistic feeders, eating whatever they can catch in the wild. In nature, they might have a few meals a day or a few days without meals.

That's what I thought, but I just want to nail down a cause.

I'm pretty sure, at this point, that he ingested some air when I was feeding him. As I lifted the lid on the tank, he stuck his nose out of the water and made a sucking noise. He may have gotten some air stuck that I couldn't burp out of him. That would explain the buoyancy issues as well as the pocket in his chest when I opened him up. Poor guy.

Mine are a similar size. I feed them twice a week.