Earlier on May 9, police summoned Bui Duc Hai, 22, native of Quynh Phu district, over the release of untruthful information about the case.
Hai admitted that he hatched an idea of posting similar articles about fish deaths with unknown causes, which have been of public interest recently.
He confessed to copying four pictures of dead fish and jellyfish and another one depicting a woman sitting on the beach and a dead fish ahead, later fabricating an article claiming that dead fish, oyster and jellyfish are drifting on shore of Con Vanh beach.
On July 5 afternoon, Hai posted the article and copied pictures on his website thaibinhplus.vn, which has yet to be licensed by the Ministry of Information and Communications.
The case is under investigation in line with the law.
Con Vanh is located inside the Red River Delta Biosphere Reserve recognised by UNESCO in 2004.
It is blessed with a system of rich and primitive mangrove forests, a well-known tourism area with a 7km-long beach and a 450sq.m swimming area.