The occurrence of off-flavour in Recirculating Aquaculture Systems (RAS) is a well-known issue for many fish farmers, inflicting significant financial losses for farmers as well as a negative perception of the RAS-farmed fish. The traditional procedure to deal with off-flavour in RAS fish is depuration of the fish in cleaner water. This approach causes weight loss and fish stress, and is also energy and water-demanding. In a newly established European network project (RASOPTA), novel instrumental and microbiological procedures are combined into a holistic approach, to help alleviate and provide new solutions to the current off-flavour issues in RAS production of commonly farmed fish within the EU.