It's called a "Waters Edge Viquarium". It's a great kit. I had one a few years back. I just looked around and it seems they stopped making them. Here is a picture of what the kit looks like. Basically, you fill the river area with gravel and the waterfall pump filters the water through the rocks. You can cover it with moss or whatever. It's looks pretty cool. If I can find mine I will let you know.
