The fishermen and their boats were detained off Terengganu state, on the east coast of peninsular Malaysia, on Friday, the Malaysian Maritime Enforcement Agency (MMEA) said.
"Checks conducted on the two boats found that 16 crew members including the skippers, aged 18 to 62, did not have any valid identification documents nor possessed any license to fish in the country’s waters," Terengganu MMEA director Captain Muhammad Suffi Mohd Ramli was reported as saying.
"Two boats, fishing gear, catch and diesel supply were also seized," he said.
The fishermen, who were suspected of using fake registration numbers, were taken for novel coronavirus swab tests before being detained, Muhammad Suffi said.