Lisa Roach, a director of Pursuit Fishing, Nelson, and Bronwyn Waters, whose husband was a skipper, were handing out pamphlets in front of Dunedin's central Countdown supermarket yesterday.
Mrs Roach said they wanted to "spread the word" that basa fish, imported as frozen fillets, were farmed in the Mekong River and could contain traces of bleach, chemicals and raw sewage.
As trawler owners, they had not been able to sell their usual catch because the market was becoming "flooded with basa" and they could not process fish as cheaply, she said.
"We don't have a problem with competition, if it is a good-quality product."
Dunedin woman Donna McIntyre said she had vomiting and diarrhoea after eating basa and had complained to the supermarket, which gave her a refund.
A Progressive Enterprises spokesman said the fish it sold were raised in a freshwater farm and tested on strict microbiological and chemical criteria before being allowed to be exported, and the product met all food safety regulations.
In a statement last month, New Zealand Food Safety Authority assistant director of monitoring and verification Glen Neal said the authority had tested 20 samples of basa and found no detectable levels of antimicrobial residues, except in a single sample of basa where the antibacterial and antifungal agent gentian violet was found at a low level.
