Double Paralympic medallist Scott Quin was in sublime form as he powered to victory in the men's 100 metres breaststroke.

The Edinburg University man claimed victory in 1min 6.04sec which translated to 900 points, giving him the win.

"I'm really happy with that swim tonight," said Quin.

"This morning was a 66.7 [seconds], so I was quite happy with that, and then I came in tonight and thought, 'I've hit that qualifying time, so I'll just enjoy myself and do something different'".

"You don't get the opportunity to just enjoy racing at meets like this - I've done plenty of these World Series meets, so I've been around here a while!"

Hannah Russell of Britain backed up a silver in the 100m freestyle by claiming gold in the 100m backstroke with a time of 1:09.62 and 854 points.

"I'm really happy with how the meet has gone so far," Russell said.

"Having the 100m freestyle up first was a great warm-up event, and now coming back into the backstroke, which is my main event, I was really pleased that I managed to duck under the 1:10 mark.

"It's really exciting."

Stephen Clegg ensured more glory for Britain after winning the men's 100m backstroke with a time of 1:01.76 and 887 points.

He built a healthy 6.07sec and 103-point lead over Spain's Iñigo Llopis Sanz in second place.

Ellie Challis of Britain won the women's 50m breaststroke final as she was the only competitor, while compatriot Lyndon Longhorne prevailed in the men's race after 58.01sec, amassing 514 points.

Clocking in after 1:34.70 saw Maisie Summers-Newton of Britain secure the gold medal in the women's 100m breaststroke with 854 points.

Gina Böttcher of Germany and Spaniard Javier Torres won gold in the women's and men's 50m backstroke events, respectively.

Böttcher finished with a time of 53.12, earning 595 points, while Torres had 620 points thanks to a 48.06 finish.

A Para Swimming World Series event is also underway in Melbourne, where all eight of the days winners were Australian.

Timothy Hodge triumphed in the men's 400m freestyle, Rowan Crothers over 100m, Matthew Levy in 50m breaststroke and Ben Hance in 100m butterfly.

The women's 400m freestyle was won by Ella Jones, 100m freestyle by Jenna Jones, 50m breaststroke by Ruby Halliday and 100m butterfly by Ruby Storm.