The Yugoslavian tug Kopacniuk active on the Danube according to a CIA report dated 10 June 1955

An item dealing with the Danube shipping movements reported that on 19 February 1955 was sighted on the position around DKM 1800 the JRB (Yugoslav River Shipping Company) tug ms Kopacnik was sighted towing 6 loaded barges upstream.

Source
The report was published on www.archive.org, document number CIA-RDP80-00810A007000090002-6