The horns were found in two bags belonging to Do Thanh Son, 38, who flew in on Monday. His flight was supposed to land in Saigon, but authorities have decided to divert all Korea flights from Saigon to Can Tho to prevent Covid-19 quarantine overload.
Upon questioning by customs authorities, Son refused to open his luggage, saying they contained koi fish and opening it without an oxygenation system would cause the fish to die.
But ignoring his protests, they opened his bags and found 11 horns weighing around 28.7 kg inside one of them.
They were seized and are being tested to determine their sources, customs authorities said. Son has been quarantined since he arrived from South Korea, a hotspot of the novel coronavirus.
The sale and purchase of rhino horns are strictly prohibited in Vietnam, but the country remains one of the biggest consumers, with people believing it has near-miraculous powers to cure diseases like cancer.