Munching on a bread roll filled with eel or pickled herring is practically mandatory during a visit to the German Baltic coast.
Smoking and serving the snacks to tourists is a money-spinning business in Stralsund - so much that the trade became dominated by what locals dubbed the mackerel-Mafia, the Berliner Zeitung reported on Thursday.
Those in control of the trade seemingly took offence at plans by Stralsund's deputy mayor to consider new rules about distributing harbour fish sandwich trading concessions last summer.
Dieter Hartlieb was beaten up outside his house and needed hospital treatment to injuries to his head and legs. A fake bomb was later left in the planning office where he worked, along with a letter which called him corrupt and told him to leave office. He has been under police protection ever since.
He told the trial of three men at Stralsund's district court that he would have had no influence over who got the licenses to sell the fish sandwiches, but that he was simply working on the rules of how it was to work.
A 34-year-old was sentenced to three-and-a-half years in prison for instigating grievous bodily harm, while a 29-year-old was jailed for three years for a number of offences including the physical attack on Hartlieb.
A 33-year-old man was jailed for two-and-a-half years for arson attacks against a fish sandwich boat and a car, both of which were owned by a hotelier who was planning to enter the business.
Questions remain about who may have been behind the attack, the paper said, although further charges have been made against another man.