Alot of people tell me when I shoot fisheye, I should turn Steady Shot off. What is the reason for this?

Also, I recently built a dolly with a track. Should I turn Steady Shot on or off when using the the camera on a tripod on the dolly with the track?

Alot of people tell me when I shoot fisheye, I should turn Steady Shot off. What is the reason for this?
Probably. Stabilization is generally done by tracking bits of the image coming through the lens. Since you're wildly distorting the image coming through the lens, you're likely to cause the stabilization to go mental.

Also, I recently built a dolly with a track. Should I turn Steady Shot on or off when using the the camera on a tripod on the dolly with the track?
Depends. If the track is dead smooth you won't need it. If it isn't, it might help. Some tests are in order.

I only use Steadyshot for handheld shooting, for the most part. I typically turn it off for anything on a tripod. It has caused some unwanted "effects" for me. Such as shifting after I have stopped a pan. Jumps in the middle of pans, Etc.

If the fisheye has vignetting, you will see it bobbling around because of the steadyshot. Even if there's no vig, sometimes the distortion will bobble noticeably.