At the 2019 World Junior Championships held in August 2019 in Budapest, Hungary, Curtiss competed representing the United States of America. In the semifinals of the 50-meter freestyle he swam a 21.95, advancing to the final and becoming the third fastest American swimmer in the 17–18 age group for the event behind Caeleb Dressel and Michael Andrew. Curtiss finished second in the 50-meter freestyle with a time of 22.14, winning the silver medal in the event.