If you can't afford a real aquarium and all its equipment, you can at least install this virtual aquarium and enjoy the view from your computer chair.
Crawler 3D Marine Aquarium Screensaver displays a complete aquarium while you're not using the PC, turning your monitor into a tank full of sea creatures.
You can choose between several aquariums and also download new fish species.
I especially liked the fact that 3D Marine Aquarium Screensaver displays some information about each kind of animal that appears on the screen; it makes the screensaver not only attractive but also informative.
On the downside, you can't remove some items like the calendar or the search field, which I personally found kind of annoying.
With Crawler 3D Marine Aquarium Screensaver you can enjoy a realistic aquarium in your PC.