The short answer is, YES!
Here's the story. Crackgerbal and I were sitting on the couch the other day (nice, ambiguous phrase, that) watching the fish. One of our fish--a simple gold fish, emphasis on the "simple" part--occasionally gets a bloated belly and has trouble not floating to the surface of the tank.
At first, we were worried he was going to die. We just started the tank about a month and a half ago and have had various goldfish dying the whole time. We thought the same toilet-type fate awaited this one. Not to be.
No, this fish likes to swallow air. He has been seen on occasion rising to the top and sucking down a bubble or two. Funny but we didn't think anything of it. Not until it popped out his ass!
There we were--just picture it--watching the fish going about their fishy daily lives when--blub!--out comes a bubble form this wayward fish's ass! Craziest thing ever. Wish we had gotten it on video. Another day in the life.
That is all