The 31-year-old Tung finished first in the men’s 50m freestyle S5 in a time of 34.43sec. Spain’s Sebastian Rodriguez took silver with a time of 34.60sec, while Mullen Andrew of Great Britain won bronze medal with a time of 35.41sec.
The southern province of Can Tho-born Tung also broke the Asian record in this category.
Earlier, Tung won a bronze medal in the men’s 50m backstroke S5 and ranked fourth in the men’s 50m butterfly S5.
Vietnam sent five athletes which featured 450 swimmers from 51 countries.
Ukraine left the event at the top of the medals table with 37 golds, 36 silvers and 25 bronzes. Russia were second with 30 golds, 31 silvers and 25 bronzes.