The term fisheye lens refers to the effect you get when no correction is made by the lens, as Mark explains above. A 16-35mm lens certainly is not a fisheye lens as the glass goes some way to correct the image, the Canon 16-35mm pulls in a liner fashion towards the extreme edges, but there is little of the fisheye (or fishbowl) effect left.

The originally linked image could be taken with just about any lens if you stitched enough of them back together, the fisheye effect is added in software. I have seem full circular 360degree versions which are just amazing !!!

Cheers

Cris