East German tug No. 255 according to a CIA report dated 14 December 1953

An item reported that after 1 May 1953 was added to the fleet of the East German Deutsche Schiffahrts- und Umschlagsbetreibe (DSU) and stationed at DSU-Magdeburg the open tug with as number 255 and capacity of 569 tons.

Source
The report was published on www.archive.org, document number CIA-RDP81-01036R000100070044-6