Where can I find a fisheye or wide-angle lens for my professional camera?And what size do I need?

first of all, you bought the wrong lens for the camera. JVC (Fujinon) makes a wide angle zoom Th13x3.5 BRMU which would be ideal for you. $8315 list price. It is the equivalent of a 0.6x adaptor for the lens you have, except it can be used full time. JVC's wide adaptor for your lens is the WCV-82sc, $651 list but it is discontinued making it hard to find. you can use any 3rd party lens adaptor that mounts on an 82mm filter thread.