;1783–1796 Fisker had a busy period during which he was part ship's captain, part surveyor and map maker of the Danish and Norwegian coasts. In 1788 he was second in command of the royal yacht
Hvide Ørn when the crown prince visited Norway. In 1789 he was promoted to captain, and in the same year he married Charlotte Amalie Kofoed, daughter of the Director of the Post Office and of the Prison Service. As captain of various ships, Fisker served in the Danish home fleet, including the ship-of-the-line
Ditmarsk, and the frigate
Fredericksværn in 1792 when this was a cadet training ship. In 1795 he travelled extensively in Jutland and the duchies of Schleswig and Holstein to determine the needs and positioning of coastal batteries. ;1796–1797 The service in home waters was broken by a year in the Mediterranean in command of
Thetis where he delivered the annual tribute to the Bey of Algiers. Fisker had diplomatic, but unsuccessful, talks with the old Bey of Tripoli, before being relieved by
Steen Andersen Bille. Among some fifty miniature portraits by Thorvaldsen are drawings of his fellow passengers made during this voyage ;1800–1805 Back in Danish waters, Fisker was on the Trindel Light commission and, on land, enquiring into sites for placements of signal telegraphs. In 1805 he was head of a squadron of various types of gunboats undergoing trials of their performance and suitability for coastal defence. ==Active Service in Norway==