Back when we had a Siamese fighting fish, we kept him in your standard-issue round bowl. We considered moving him into a pretty vase of some sort, but never got around to it. Just last week though, we came across an example of this: At Area in Jackson Square, shop proprietor John Giacomazzi has a pair of fish to keep him company.
John's nieces picked out Lucy and Roxie from a pet store just up the street, in Chinatown. And he's given them the coolest home we could imagine. Nothing over-the-top; just a simple and elegant vase with a bit of greenery and river rocks inside. The lovely Yves Behar "Leaf" lamp illuminating the vase/fishbowl is also a nice touch.
The vase can be picked up at Area for about $150.