The fishermen were found off Aur Island in western Malaysia on October 24, The Star reported Friday.
Their fishing tools, the fish caught, fuel and other equipment on the boat were confiscated.
The crew failed to present the licenses of their vessels to Malaysian authorities. Some members could not provide any identification papers.
The incident is being investigated under Malaysia’s Fisheries Act 1985, the newspaper quoted Malaysian Maritime Enforcement Agency (MMEA) director Mohammed Zulfadli Nayan as saying.
Many Vietnamese fishermen have been captured for illegal fishing in foreign territorial waters in recent years.
Earlier this month, two vessels and 39 Vietnamese fishermen were detained for fishing illegally in Malaysian waters.
Last month, a Vietnamese fishing boat and its five crew members were caught off Palawan, western border of the Philippines, as reported by GMA News.
Vietnamese authorities are putting efforts in improving awareness of marine boundaries and international maritime laws, and allocate regular patrols to prevent potential violations.