So how did the goldfish get in there, if the neck of the bottle is about a fourth the size of him? I can only hypothesize that he grew in there. I don't think vodka could sustain his breathing, either. He couldn't have grown in there while the vodka was being created, either, since you need a still.

Only thing that really adds up, is he grew up with water in there like a regular fish tank, they emptied the water from it, and filled it with vodka.

A few minutes of thinking on something so trivial...well spent.