Fisher stormed home in just 30 strokes to card a second- round 65 on the 7,964-yard, Ernie Els-designed Copperleaf course, the longest in European Tour history.
That gave the 33-year-old former Ryder Cup player a halfway total of 13 under, one ahead of Denmark's Morten Orum Madsen who also returned a flawless 65.
Fisher was only one under par at the turn after a birdie on the first was followed by eight pars, but he picked up further birdies on the 10th, 13th, 16th and 17th, along with an eagle from 40 feet on the 15th.
"It was pretty special. Any time you can do that is very pleasing," Fisher said.