Schuster spent the first six years of his life in Fiji before moving to Samoa with his parents. His mother Suzie is also his coach.
"The first 100 metres was butterfly and I'm not strong in butterfly. I didn't really see the swimmers in front of me, but somehow towards the end of the race I don't know where the energy came from and I just swam hard to claim third place," Schuster said.
He stopped the clock at 4:36minutes behind New Zealand swimmers Blake Gunn who came in second (4.35min) and Andrew Trembath (4.35min) who won first place.