Larne swimmer Danielle Hill improved her own Irish 100m backstroke record at the McCullagh International meet.
Hill, 20, clocked 1:00.90 to cut 0.18 seconds off her previous mark as she took second behind Britain's European medallist Kathleen Dawson [1:00.28].
Another Irish Olympic hopeful Mona McSharry won the women's 50m butterfly as her time of 27.14 left her 0.32 ahead of Welsh woman Harriet West.
Sligo native McSharry then took second in the 200m breaststroke in Bangor.
The 20-year-old clocked 2:27.44 as Britain's 2016 world short course champion Molly Renshaw won in 2:26.79.
World championship silver medallist James Wilby won the men's 200m breaststroke as his time of 2:11.23 left him 1.81 ahead of Scotland's former European and Commonwealth Games champion Ross Murdoch.
Ireland's Shane Ryan took second in the men's 100m backstroke, 0.16 behind Britain's 2019 world championship bronze medallist Luke Greenbank who won in 55.02. Northern Ireland's Conor Ferguson completed the podium positions in 55.50.
Britain's 2019 world bronze medallist Duncan Scott produced the fifth fastest time in the world this year as he won the 200m freestyle in 1:47.06.
Scott's time left him 1.22 seconds ahead of Northern Irishman Jack McMillan.
There was a British sweep in the women's 200m freestyle as Loughborough's Abbie Wood won in 1:59.96 from Sunderland's Alys Thomas [2:00.54] and Stirling's Aimee Wilmott [2:00.96].
Commonwealth Games silver medallist Daniel Jervis added 1500m freestyle gold to the 800m he won on Friday as he clocked 15:09.35.
Ulster swimmer Amelia Kane also completed an 800m/1500m double as she won the shorter event on Saturday in 9:09.32.
The Bangor event is following the same format as Tokyo, with evening heats followed by morning finals.