The A final was won by Wellington's Gareth Kean in 53.97 which was more than one second inside the qualifying mark for the world championships in Barcelona in July.
Others to achieve world qualifying marks on the second day of the opens were Lauren Boyle, who produced a stunning swim to break her own national record in the 1500m freestyle, and fellow London Olympian Matthew Stanley who was nearly half a second inside his own New Zealand record when he won the 200m freestyle. Boyle's time of 16.16.83 was the second fastest for a female in the world this year.
Meanwhile, Paralympics stars Sophie Pascoe and Mary Fisher took the limelight at the national championships yesterday morning as they claimed world records.
Pascoe clocked 29.21s in the 50m butterfly which broke her own previous world best of 29.57s, set at the London Paralympics.
Her fellow London gold medallist, Fisher, was timed at 34.35s in the same event, breaking her own world record of 35.12 in her impairment group.
United States-based Glen Synders went under the qualifying time for the world championships when he led the qualifiers in the heats of the men's 50m breaststroke. His effort of 27.41s was more than half a second better than that required for him to compete over the shorter distance at Barcelona after he had already qualified in the 100m.
