The blaze broke out at about 1 pm at the Khe Da anchorage, on the border between Quy Nhon Dong Ward and Tuy Phuoc Dong Commune.
Firefighters deployed multiple fire engines and dozens of personnel to the scene, but efforts to contain the blaze were hampered because the anchorage was located far from shore.
Authorities said the fire had been brought under control. Most of the damaged vessels belonged to fishermen from other parts of the province who had moored their boats at the site.
No casualties were reported, but all 12 fishing boats were destroyed.
Local fishermen said most of the boats were older squid-fishing vessels worth between VND 150 million and VND 300 million (USD 5,700-11,400), although replacing each vessel would cost close to VND 1 billion.
Authorities are assessing the damage and investigating the cause of the fire.