"This will be the 'party party' of my lifetime," Madsen, from Sweden’s Surströmming Academy, announced as he opened the tin in front of the phalanx of television cameras who had come from Norway, Sweden and Germany for the event. "Our whole life circulates around this, but this here takes the prize."
When the can was opened, the onlookers gasped at the sudden, appalling odour.
"The smell was terrible," Madsen told The Local. "At first when I opened the can, it smelt really good, but within 15, 20 , 30 seconds, when the oxygen started to affect the brine, it started to smell really, really bad. Normally surströmming smells really aggressive, but this was worse. It was terrible."
However, to his disappointment, once he studied the contents of the can, he discovered that twelve fish that were once inside the can had dissolved into the brine.
"The release was a big success but the opening was a big mess," he said. "It was impossible to eat. It was some kind of rotten porridge. It was impossible to taste it."
Madsen had travelled to Norway from his home in Sweden after Inge Haugen, a pensioner in Tyrsil contacted the Academy, as he was worried that the can, which he recently found lodged in the roof of one of his cabins might explode.
The can had been left over from a party he and his wife Bjørg Hennum had held in 1990.
"It is a relief," Hennum told The Local. "Now we are no longer afraid for the roof or anything."
She said that she had enjoyed hosting the 80 or so journalists and surströmming aficionados who had come to witness the event.
"It was a good atmosphere," she said, adding that the smell had already dissipated in the winter air. "It smelt a little bit, but now it's OK. I can't say what it smelt like but it was not good."
This evening she will host a party in which both surströmming and its Norwegian equivalent rakfish will be served.
Madsen said removing the can, which had raised the roof by some two centimetres as a result of swelling, had been tougher than he expected.
"It was more dramatic than I thought because it was quite difficult to remove it from the cottage," he said.
He said he had worn protective head and eye-wear "in case of emergencies".
"If there would be a leakage, the salted water and the fermented brine would have sprayed in my eyes, and I didn't want that," he said. "It was really dramatic to be honest, because the whole cottage started to move and I was afraid it would collapse over my fingers."