The vessel was intercepted on Tuesday about 86 nautical miles off the Bo De Estuary in the southern province of Ca Mau during a patrol by Coast Guard Region 4.
The boat was carrying seven crew members and about 20 tonnes of seafood, but its captain was unable to produce registration or other vessel documents, the coast guard said.
Officers found the vessel had three vessel monitoring system (VMS) devices installed, but only one was transmitting a signal.
Checks against the national vessel monitoring system found the boat's registration details did not match its displayed registration number, indicating the use of a fake registration and other serious IUU violations.
The vessel was escorted to shore for further investigation and legal action.
The Coast Guard Region 4 Command said it has recently stepped up patrols along waters bordering Malaysia, Thailand and Cambodia to prevent illegal fishing and stop Vietnamese fishing vessels from entering foreign waters.
The measures form part of Vietnam's efforts to secure the removal of the European Commission's "yellow card" warning over the country's seafood exports.
