If you don’t know what this fish is, you should check out the story of this "beta" fish that first was introduced in Windows 7 Beta. Microsoft hand picked this particular fish as the default wallpaper in the beta release of Windows 7 is because this Siamese fighting fish is also known as the Betta fish, the same pronunciation as beta.
The betta fish has made its way back as the default wallpaper in Windows 8 Consumer Preview, a public beta version of next generation of Windows but only as a carton version of it this time. But the Bing team actually made up a version of this Betta fish not only real on its Bing page but also swimming lively across the page.
Check it out with this particular Bing Link.
As a side note, the Betta fish is probably one of the easiest fish to take care of at home on earth. If you are a geek you probably should think of putting one in your office to make your workspace a more fun place to work.