Having both 8mm and 16mm fisheye lenses, albeit not the Zenitar, I'd caution about the amount of "fisheye-effect" you're likely to get on an APS-C camera with a 16mm lens. If you really want extreme distortion, an 8mm lens will be far more satisfactory, the 16mm is little more than a poorly-corrected wide-angle on the small sensor.
My Peleng 8mm was always "a bit of a novelty" on full-frame film, but really comes into it's own on APS-C, with only a little vignetting in the extreme corners of the frame. My Fujinon 16mm however, often a "weapon of choice" on film, gets very little use these days!
YMMV