Sorry to repeat myself but the answers can be found here
This is from the article....
"The adjusted temperature should be maintained for approximately 10 days, or a minimum of 3 days after all signs of the parasite have disappeared. Do not discontinue treatment when the spots go away. This is critical, because we know that they are visible only as a trophont on the body of the host, and not during the reproductive or free-swimming stage. We also know that trophonts on the gills are impossible to see."