The main purpose of the "Aquarium" or "Fish" demo is to demonstrate mobility and context-independence of Envoii objects - breaking "out of the box" of the browser. While cut 'n paste is increasingly supported within the (AJAX) browser experience, stateful mobility is not. Thus, the fish retain their identity as they are dragged from the browser to the desktop or to other envoii "places".
After you have downloaded the demo, drag the fish out of the demo window onto your desktop.
To stop the demo, right-click on the Envoii icon in your system tray and choose Exit.