You could build some kind of octopus's garden in there, with no octopus. It could have plants and shrimp, but as I type that, I realize I still don't like shrimp. I might be influenced by that.
Tall, cylindrical tanks are not a good design for the things that live in them. One paradise fish? Sir William Penn, in 1666, had one in a large vase. So it has been done before, although not for long, apparently. He also probably fed it bread, none of which stopped getting a state named for him.
The traditional fish would have been a goldfish. Everyone would know it was going to die, but who cares about the life of a goldfish? They're cheap and expendable ornamental fish. As fishkeepers, either we go full steam ahead on that way of thinking, or we look at it as ugly and go in the opposite direction. The real nano tanks on youtube reflect that first, traditional way of thinking.
The one and only fish would be a fancy Betta, and that because they are generally mistreated and deformed, and a jar wouldn't be a lot worse than some of the kits that are sold for them. A lot of people on the forum have argued for better treatment of Bettas, some for years and decades, so you won't get a lot of support for the idea.
We're a bundle of contradictions, as we'll rip up the mouth of a fish with a hook for fun, leave it to asphyxiate on the bottom of the boat, eat a fish, and then worry about humane treatment in a jar. I know. There is no high ground in these discussions. We're strange.
Plants in a jar could be cool, but technically, beyond my skill level. I'd end up growing algae.
