Local seafood exporters have criticized a European parliament member who has alleged that the pangasius or tra fish is farmed in "filthy" pools and polluted rivers.
They've asked Struan Stevenson of Scotland to visit the farms on the Mekong River and see the breeding pools for himself.
In his keynote address to the European Parliament last week, Stevenson said the river where the fish are raised was one of the most polluted rivers on earth and that factories along its banks daily pumped thousands of tons of contaminants into its slow-moving waters.
"As a result, the water is teeming with bacteria and poisoned with industrial effluents including arsenic, mercury and DDT," said Stevenson on his website www.struanstevenson.com.
In his speech, Stevenson also said imports of the cheap fish were undercutting European fish farmers and allowing multinational firms to exploit virtual "slave labor" in Vietnam.
Stevenson said the fish was farmed by "slave labor" paid US$1 per day, a situation ruthlessly exploited by some major multinational companies.
Truong Dinh Hoe, general secretary of Vietnam Association of Seafood Exporters and Processors (VASEP), said Vietnamese aquaculture farms maintained very strict global standards of quality and seafood products exported from the country met stringent standards required by international markets.
"Most of our industry's processing plants not only meet HACCP (Hazard Analysis and Critical Control Points) standards, but also meet or exceed other voluntary standards such as those set by the British Retail Consortium, the US Department of Commerce, and SQF 1000," said Hoe.
The SQF 1000 system is a HACCP-based supplier assurance code designed to meet the needs of primary producers.
Hoe said many of the association's members were also preparing to acquire Best Aquaculture Practices audits and certifications.
"We believe that once you see how our products are grown, harvested and processed, you may wish to correct the record by speaking from first-hand knowledge and experience," Hoe said. VASEP represents nearly $4 billion worth of fish and shellfish exports a year.
Hoe said Vietnamese firms were working hard to grow and innovate in the face of the higher costs of feed and other raw materials, a demonstration of the country's commitment to becoming a global producer of the much-needed protein.
Stevenson, though, alleged that pangasius was already being sold at rock-bottom prices under names including basa, grey sole and Vietnamese river cobbler by UK supermarkets, fishmongers and fish-and-chip shops.
He said UK sales of frozen pangasius have rocketed by 50 percent to nearly 1,500 tons, while sales of traditional species like cod, salmon and trout have dropped in the past year alone.
The volume of fresh sales is unknown but is likely to add significantly to the total, he added.
Imports now account for 60 percent of fish consumed within the EU, worth 25 billion pounds ($39.5 billion) last year, including an astonishing 224,100 tons of pangasius from Vietnam, according to Stevenson.
"Let's encourage more investment into innovative EU aquaculture projects so we can meet the rising consumer demand for first class, fresh and healthy fish produced in a sustainable and carbon efficient way," Stevenson said.
"We must persuade our consumers to buy local. The EU is well placed to seize this opportunity. Don't let us miss this chance," he added.