It was the perfect ending, he says after winning in a championship record of 3:41.28.
It was 1.32 seconds faster than German Lukas Märten's world record set in Stockholm in 2025.
No swimmer has previously won seven gold medals at the Asian Games. Sarah Sjöström's competitor Rikako Ikee of Japan held the previous record when she won six gold medals in Jakarta in 2018.
"I was calmer than I expected," Zhang says of the build-up to his historic gold.
Zhang also won the 200, 800 and 1,500 metres freestyle, as well as three team events during the week.
At world championship level in long-distance swimming, the 19-year-old has never won an individual medal, but has two golds and one silver in the team event.
