Is the AF DX Fisheye-NIKKOR 10.5mm f/2.8G ED compatible with my nikon d3000?

Http://www.nikonusa.com/Nikon-Products/Product/Camera-Lenses/2148/AF-DX-Fisheye-NIKKOR-10.5mm-f%252F2.8G-ED.html#tab-ProductDetail.ProductTabs.Overview

http://www.nikonusa.com/...D3000.html

It is.

I have used it successfully with the old D40 that the D3000 replaced.

Interesting… I didn't know that there are DX lenses that are not AF-S or at least AF-I.

Yes, it will work and meter, but it won't autofocus on the D3000. But due to the naturally extremely deep depth of field of a ultra wide angle or fisheye lens, using manual focus is very, very easy. Just set it to the hyperfocal distance (in that case, 6 divided by the aperture f-number meters, i.e. 1 m at f/6 or 2m at f/3) and be done with it.