Management duo Wiesinger and Reutershahn were sacked on Monday night following a 5-0 home thrashing by Hamburg 24 hours earlier.
A club statement claimed a new manager would be unveiled soon, with under-23 boss Roger Prinzen taking over on an interim basis.
Nurnberg chairman Martin Bader told the club's official website: "After the heavy 5-0 defeat to HSV and the events of the season so far, we made the decision to take this step after some intensive discussions.
"It was a difficult decision, but it was the right thing to do in the interest of the club.
"It wasn't easy to tell Michael and Armin. Both of them identify themselves strongly with the club and they always worked with heart and soul.
"Unfortunately, the last few games have shown that there is no upward trend."
Wiesinger and Reutershahn took charge following the surprise departure of Dieter Hecking to Wolfsburg in December 2012.
The duo claimed 24 points in the second half of last season to guide the club to a 10th-placed finish.
But Nurnberg have found things tougher in 2013/14, the Hamburg defeat their eighth Bundesliga game without a win since the start of the new campaign.
Speaking before the axe fell, Wiesinger was confident he and Reutershahn could turn it around.
He told Kicker: "It is clear that questions will come.
"That (the Hamburg defeat) was a real setback. Now we have to process it. We now have two weeks to lick our wounds. They are deep wounds.
"We will continue to find solutions and this time we will find a solution."