The Royal Thai Navy impounded three Vietnamese fishing boats disguised as Thai vessels to illegally fish the Gulf of Thailand.
The crew of Patrol Boat 271 arrested eight crewmen from the boats which had changed their names to Thai script and flew the Thai flag about 39 nautical miles off Koh Chuang.
They were charged with illegal fishing and illegally entering the kingdom.
The boats came out of Phu Quoc, Vietnam to fish for squid.
Since October, there have been 34 arrests and 71 boats seized in the Gulf of Thailand.