The former Iran national swimmer hung up the goggles in 2011, turning his focus to coaching his country at the Olympics.
But when Deljoo, 36, moved to New Zealand in 2022, he started working for former New Zealand swimming coach Mark Bone, who told Deljoo he was too talented to just focus on coaching swimming.
Masters sport is not popular in Middle Eastern countries, but the New Zealand Masters Games opened up new opportunities for him to get back in the pool.
Bone’s advice was right, leading Deljoo to win seven gold medals at the Whanganui games last year.
Keen to see how far he could go, Deljoo headed to Dunedin for the Masters Games, where he broke all expectations, winning 12 golds, to bring his total to 19 medals across the games.
Traditionally a breaststroker, Deljoo was thrilled at his medal tally and the chance to dive head first into competition again.
"The environment of New Zealand encourage people they can achieve their goals whenever they want", Deljoo said.
"I didn’t swim for a long time, but right now ... I’m practising at least five days every week because of this competition, because of this opportunity, because of these people and because of this culture."
Having always encouraged his own swimmers to work hard to reach their goals, Deljoo was pleased to be able to show them that hard work pays off.
"I believe the Masters Games of New Zealand is really ... a family competition, which is absolutely lovely.
"Right now, I’m really happy.
"I feel I’m more healthier than before."
Deljoo started swimming in Iran when he was 4, and moved through the ranks as a national age-group swimmer.
He competed at the West Asian Games and finished fourth at the Asian Games before turning to coaching.
"It was a really good and brilliant time for me.
"I believe that background, it’s helped me a lot to improve my swimmers."
He coached Iran through the age groups from 2011 to 2018, including at the Olympic Games, before moving to Oman to further his coaching career.
Looking for a change, Deljoo moved to New Zealand in 2022, settling in Auckland, working for Bone as part of his management and coaching team.
"He is an absolutely fantastic leader."
After completing a degree in sport physiology from the online California Centre University, Deljoo started studying online through the University of Otago towards an applied management degree.
"This was a very good opportunity for me to visit my university and participate in these brilliant games", he said about visiting Dunedin.
He also helped as a coach at the World Championships over the past two years.
