The Pools striker has been with Dundee since August and the two clubs have now come to a new agreement allowing him to stay at Dens Park until the end of the season.
Since returning north of the border, Nish has found the net twice in sixteen outings for The Dark Blues who are currently bottom of the SPL.
The 31-year-old's move has gone through in time and he should be available for Dundee's trip to St Johnstone this afternoon.