SereneScreen's Marine Aquarium is a very famous and classic 3D tropical fish aquarium screen saver. It has won numerous software awards and topped the download ranking of many software download websites. Even better, it was recommended by Microsoft and included in their Microsoft Plus! for Windows XP (AKA: WinXP Plus Pack) - as this OS's official/built-in screensaver. Plus, it is so popular that many computer sellers use it too, you may have noticed this.