Fish diseases are a major concern for aquaculture where fish are commercially reared. In the Nordic-Baltic countries aquaculture is currently taking place in freshwater fish farms and in marine fish farms. A range of viral diseases can cause devastating losses to fish rearing and wild fish stocks. Viral hemorrhagic septicemia (VHS) – also known as “Egtved disease” - is a viral fish disease which affects a large number of freshwater and marine fish. The rainbow trout is very susceptible to the disease. This report provides information on the preparatory work and the conduct a simulation exercise code-named “TROUT 2013”. The aim of the exercise was to test National VHS Contingency Plans.