Environmental police have fined eight seafood factories in the southern coastal city Vung Tau a total VND2 billion (US$89,000) for discharging untreated wastewater that caused fish at local farms to die en masse.
Officers at the Ministry of Public Security said the factories had been using portable pumps to discharge their wastewater into a local river for between two and four hours every day over the past few years.
Nearly 200 families whose fish farms are located downstream of the Cha Va River have complained about the pollution and dead fish for years.
On September 7 some of them brought hundreds of kilograms of dead fish to Ba Ria-Vung Tau Province government office to protest the ongoing problem, one day after they did the same in front of the seafood firms.
Officials then estimated that the farmers lost around VND10 billion ($451,000) from the dead fish, with the most affected family losing more than VND1 billion worth of fish.
But now they said the damage was just half of that.
They have halted the operation of the companies waiting for further test results from their waste samples for more punishment if necessary.
Truong Thi Huong, deputy chairwoman of Vung Tau People's Committee, said the farmers lost more than VND100 billion in similar incidents last year.