[Randy]

"Fatty" lives in a tank at a buddy's office. He's so fat that he tends to flip upside down and stay like that for an hour or so before managing the strength to roll back over.

upsidedown2

[Scrooge]

I think it's gas. My son's got a 16" Koi that does that, bloats up after eating and turns over on its side and swims around that way.

[polarbear]

You need to tie a weight to its underside. Do fish have navels? Are they into navel piercing?