One of the challenges you (and many of us) are going to have is that your camera doesn't have a full 35mm image sensor. As opposed to a full frame sensor your camera has what most call an aps-c sensor which is only about 40% of the full frame size. This matters why? Because you must take the focal length of your lens and multiply it by approx 1.5 or 1.6 to get the effective equivalent of 35mm lenses. Since a fish eye lens would be around 8 to 15mm, if you get the 15mm and multiply it by 1.6 you get an effective focal length of around 23mm which is basically a nice wide angle. If you by an 8mm you could still manage the equivalent of 13mm, but I am not sure what is available for you.

Hope this helps - Mike