The fishermen were arrested on November 26.
The Judicial Magistrate of Mannar extended the remand when the fishermen were produced in the court today, Fishermen's Association president S Emiret said here quoting information received by him.
Earlier two Lankan courts on December 21 and one court on December 23 had extended the judicial custody of 16 and 35 fishermen from Tamil Nadu, respectively. They were all arrested on similar charges by Lankan Navy in November and early this month.