"It is something that is a dream job for me, something I won't take for granted," said Fish during a conference call. "To be the next Davis Cup captain is incredibly humbling.
"I can't express how excited I am... that the players have supported the decision," added the 37-year-old.
"Everyone is really excited about the idea of the reform and the new format, sort of a World Cup of Tennis.
"It is going to be interesting from all parties to see how it goes."
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Fish will take charge in a dramatically different Davis Cup format from the one in which he played in 11 ties from 2002-12.
Instead of the three-day ties that used to take place a few times during the year, it has been overhauled into an 18-team event that this year will be played from Nov. 18-24 in Madrid.
The new format will also bring a change in duties for the U.S. Davis Cup captain, who will work closely with the United States Tennis Association (USTA) player development programme.
Fish will spend much of the year travelling to tournaments and camps to support and mentor young American players while integrating current players with future professionals.
"Helping any and all of the players, mentoring players new and old, present and future is just something I am very passionate about," said Fish, who made it to the quarter-finals of three of the four Grand Slams.
"Trying to build that team camaraderie around everyone.
"All the way down the list I want everyone to feel part of Team USA.
"I went through a lot of ups and downs in my career, it wasn't because I wasn't a hard worker. It was because I didn't truly understand what it took to get everything out of what you have," added the American, who during his playing days admitted he suffered from a severe anxiety disorder.
"Understanding the professionalism and dedication it takes on a day-by-day basis, I want to try the best I can to motivate those guys and show them."
After retiring as a player in 2015, Fish, who had a career high ranking of number seven, worked as part-time coach with USTA Player Development, helping to guide young Americans on Tour, including Taylor Fritz and Jared Donaldson.
(Reporting by Steve Keating in Toronto. Editing by Pritha Sarkar)
