Japanese style fish tank?

[Brock Fluharty]

Ok, well I am redoing my room with a heavy Japanese theme. Shoji screens, tatami mats, the whole shebang. I was just wondering if anyone knew of any fish (freshwater or saltwater) that are indigneous to Japan. I wanted koi, but an indoor pond on the second story and a 1000 gallon tank are both sort of out of the picture . So can anyone think of anything that will still go along with the Japanese theme? oh, btw, the tank in my room is a 20 gallon. I know of some small squid that would fit the size, but I, personally, would not feel comfortable getting any kind of squid until they are better understood. Thanks!