“I wanted to come to Berlin and it's the biggest U-Bahn system in the German-speaking world,” the Leicester, UK native told The Local.
He and local friend Ana Campos made the entire circuit in a total of eight hours, two minutes and 57 seconds, although they don't know whether they're the fastest ever as there's no official record.
In Berlin, Fisher held himself to the simple rules he observed when setting his New York record in November 2013: arrive or leave at each station by train, visit every station (but not every stretch of line), no breaks, and all changes by public transport or on foot.
A serious competitor in the small world of subway tour record chasers, Fisher wouldn't reveal anything about his route around the capital's 173 stations and 10 lines when interviewed during his dash.
“The route is secret,” he said. “If you lot know where and when I start, then you'll try to copy me!”
He invited reporters to join him on the only complete line on his circuit, the U1 from Warschauer Strasse to Uhlandstrasse.
Competitors generally don't travel entire lines as it would be time consuming to get from the end of one to the start of the next.
But they must use other forms of public transport or their feet to get between stations when changing lines.
Riding the rail
Fellow passengers were bemused by the group of journalists swarming around Fisher,who was only slightly out of breath as he bounded onto the train with just a minute to spare - although he was half an hour behind schedule.
"The timetable has gone wrong," he said regretfully. "We were too slow on the changes, we thought we'd have more time than we did."
"I haven't had time to research as much as I want."
He said that Berliners have generally only been mildly puzzled by a man sprinting through U-Bahn stations in glasses and sports gear, taking photos of signage at every stop and noting down arrival and departure times.
“Some laugh, some just shake their heads, just general bewilderment,” Fisher confirmed.
He has been travelling the world's metro systems, including the London Underground, Paris Metro, Boston T and others, for the past 10 years in his quest to set records.
Compared with other subway systems, Fisher says, the Berlin U-Bahn is “among the simpler ones to navigate, but it's also quite big, it has 173 stations.
“[I do this] because I want to. It's just something to do,” he told reporters asking about his motivation.
“I've never lived in London but I've been a regular visitor,” he added. “Taking the Tube has always been a novelty for me.
“One day I wondered if it were possible to go to every station in one day. I discovered there was a world record for it and started with that.”
Map to success
Fisher's love of maps may also have something to do with his fascination for urban light rail.
“I just like maps generally,” he said. “I find all maps interesting, the way that the lines are drawn and whether the station names overlap any of the lines and stuff like that.
“I have a large collection of late 90's and early 2000's A-Z's.”
In fact, Fisher has spent so much time poring over maps and scouting out potential routes around the city's public transport network that he hasn't seen any of the sights.
“I'm not a sightseer,” he says. “I saw Brandenburger Tor, but that's only because I was researching the station and I had to cross the road. That's the only thing I've seen.”
Getting off the train
However, there were a few things he wants to see in the German capital before leaving on Monday.
“I've heard great things about the Bear Pit Karaoke and Mauerpark's a bloody festival on Sunday afternoons, it's incredible, I've never seen anything like it.”
A Berlin Transport Company (BVG) spokeswoman said that they weren't aware of an existing record for reaching every single station, but Fisher is far from the first to attempt it.
“That young people want to visit every U-Bahn station in a certain time, that's not new,” she told The Local.
“It might be a lot of fun, but if you really want to get to know Berlin then I suggest you get off the train,” she added.
SEE ALSO: U-Bahn sex pair shock commuters