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Brazilian consumers have been misled for at least seven years by fisheries who sold them catfish disguised as a made-up fish species, research reveals.
A study of the DNA of fish fillets found that a fish branded as douradinha, which first appeared in Brazilian markets and shops in 2008, is being used to disguise fillets from other types of fish, including piracatinga. Piracatinga is a catfish that is considered disgusting in Brazil because it feeds by scavenging, and is not normally eaten by humans.
Haydée Cunha, a geneticist at the Federal University of Rio de Janeiro and lead author of the study, says her team became suspicious when they failed to find any fresh douradinha in the market. Instead, the fish was only available as frozen fillets.

“Only if people stop buying [douradinha] will the markets no longer sell it.”

Haydée Cunha, Federal University of Rio de Janeiro

“It did not correspond to any fish of the Brazilian Amazon,” Cunha says.
Cunha and her team genetically analysed 62 fillets labelled as douradinha bought from supermarkets and street vendors in Manaus and Manacapuru, two of the largest cities in the western state of Amazonas. They then compared these with samples of piracatinga from a Manaus market and the Mamirauá nature reserve, also in Amazonas.
“The DNA could tell the story,” says Cunha, “and unequivocally showed us that much of the douradinha was actually piracatinga.”
As well as more than 60 per cent of the fillets turning out to be piracatinga, the researchers found the rest comprised other low-value fish species.
Moreover the study, published in a special issue of the Journal of Heredity in September, found traces of Amazon river dolphin meat in two samples, indicating its use as bait. The practice of killing this endangered species to use its meat as bait when fishing for piracatinga has spread across South America.
In Brazil alone, an estimated 1,650 dolphins are killed every year to be used as bait, the paper states. But Cunha’s study is the first to provide genetic evidence for this, says Susana Caballero Gaitán, a molecular ecologist at the University of Los Andes in Colombia. The new study is part of a growing body of evidence of large-scale fish fraud in Brazil. Earlier this year, a five-year government moratorium on the sale piracatinga in any form came into force to give officials time to create regulations to deal with the problem.  
But despite this step, Cunha fears fishing companies will find other ways to keep selling this species. “Only if people stop buying [douradinha] will the markets no longer sell it,” she says.
Caballero Gaitán agrees. “Only a change in the market can prevent the companies from pulling the wool over our eyes,” she says.
This article first appeared on SciDev.Net’s Latin America and Caribbean edition.


Haydée A. Cunha and others When you get what you haven’t paid for: molecular identification of “douradinha” fish fillets can help end the illegal use of river dolphins as bait in Brazil (Journal of Heredity, September 2015)