Björn Lundgren, who produces fermented herring with his brother Lars on the Rovögern peninsular outside Umeå, said that the idea of using roach – another fish – as a herring replacement had come from the musician Stefan Sundström, a friend of the brothers, after they complained of a shortage of herring in the area. 

“It was partly because it would be tasty, but we also did it as a little bit of a joke,” he said. “There’s a big shortage of herring, but there’s a lot of roach.” 

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The roach, known in Sweden as a mört, is common both in lakes and in coastal areas of the Baltic Sea. 

The Lundgren brothers have so far prepared around 50kg of fermented roach, experimenting with different recipes alongside Sundström. At least one, they claim, had very tasty results. 

When Julia Hedlund, a reporter in Västerbotten for state broadcaster SVT, tried the new delicacy, she was doubtful, however, reporting that the powerful aroma “gives you a foretaste of what is to come”. 

“Oj,oj,oj,” she says on a clip after tasting the roach. “That taste is going to stick with me for the whole day.” 

The brothers are now considering putting a much larger quantity of roach in their fermenting barrels this summer, with as much as 500kg in production.

“It takes a pretty long time to prepare – seven months or so – and then we’re thinking of canning it and put it up for sale to the general public,” Lundgren said.