The crabs, found in Binh Thuan and Quang Ngai Provinces, are being sold at VND500,000-600,000 ($20-24) per kilogram in Ho Chi Minh City.
Tram, a vendor in the city, said they are in high demand due to low supply of mature crabs. Lan Anh, another vendor, said she has sold 120 kilograms in over a month. They are in high demand because of their firm and flavorful meat, she added.
Juvenile crab prices have risen by 10% year-on-year.
But the surge in demand is leading to a depletion of marine stocks, industry insiders warned, explaining that fishermen used to release juveniles back in the sea but not any longer.
Adult king crabs cost triple the prices of juveniles.