He was one of 30 people on board a purse seiner, which arrived in the Marquesas islands to seek urgent medical assistance.
The ship, the Charo, anchored in an uninhabited bay off Nuku Hiva where doctors tested all 29, with results expected tomorrow.
Media reports say the entire crew showed signs of Covid-19.
The French military flew one of the men to Tahiti in an operation which also involved the urgent medical aid service, SAMU, and the Joint Rescue Coordination Centre in Tahiti.
The ship had been at sea for a month.