Would be a great tank for a school of thin, agile, fast swimming fish. Figure something like chela dadyburjori, espei barbs, danios, hemmigrammus rodwayi etc... Any of the fish Amano would use in an iwagum layout would be perfect for this setup. You definitely want fish that will make use of the length of the tank, but given the width and height, I'd go with a relatively small (no more than 12 imo) group in order to coerce them into schooling a bit more tightly. Gotta 2nd the hillstream idea. This tank could be perfect for many of the smaller hill and brookstream loaches. Imagine a sag meadow blowing down the length of the tank with the current, interspersed with some bold chunky rockwork. Sounds like an awesome tank with great possibilities. Hope this comes to fruition for you.