Health impacts from parasites of farmed Southern Bluefin tuna (SBT), and management of those impacts, have a significant effect on industry productivity and profitability. Up until 2007, the research effort seemed to largely address the potential risks because total mortalities from all causes in the farms remained 2-3%. From 2007 mortalities accelerated to a peak of 14% in 2010. The blood flukes, Cardicola forsteri and C. orientalis, were identified as the cause of the mortality increase, and a polychaete as the intermediate host. The treatment for blood fluke developed under FRDC project 2008/228 was praziquantel (PZQ), also widely used in Japan for farming Pacific Bluefin Tuna (Thunnus orientalis) and for Atlantic Salmon. Despite the success of the praziquantel treatment for SBT, the view of the SBT industry is that health management should be continuously improved as it significantly contributes to productivity. Infection dynamics appear to have changed since praziquantel is being used. We do not yet understand the infection dynamics or best strategies to manage blood fluke infection. One possibly important step is to assess the blood fluke levels in treated and untreated pontoons. In 2016 one company left a pontoon untreated and had similar outcomes to their treated pontoons – and in 2018 three companies are trialing the same approach.