Witnesses said that a 43-year-old tourist from Norway started to berate and provoke a German man on Sunday night while on a regional train, according to Berliner Zeitung.
Police reported on Monday that the man's insults in English led to a physical confrontation between the two men.
A Berlin man, 37, stepped in to try to break up the fight, but the tourist then bit his right ear and tore off a piece measuring several centimetres long.
Other passengers managed to then restrain the Norwegian until the train stopped at Karlshorst station in eastern Berlin and police could arrest him.
The 37-year-old was bleeding heavily and was taken to hospital.