Seto put in the most impressive individual swim as he won the men's 400 individiaul medley in a time of 4:00.02 which broke the Asian record and was also the fastest time recorded in a World Cup race.
Hosszu meanwhile continued her simply stunning World Cup form with three more victories bringing her season total up to 33 gold medals.
The Hungarian won the 800m freestyle, the 200m freestyle and the women's 200m individual medley.
Each win on the World Cup circuit is worth $1,500 and the overall leader at the end of the eight-leg series bags a $100,000 bonus.
That looks a guarantee for Hosszu who has banked $56,250 already – more than double second place Zsuzsanna Jakabos ($27,750 ) - with just one and a half meetings left.
Seto meanwhile is the top male earner with $24,500 – with Robert Hurley next on $19,750.