Abstract: The study of swimming of fish is essential for our understanding of the interplay between migration, growth and reproduction in wild fish but also has considerable interest for fish in aquaculture. The main objective of the COST Action FITFISH is to develop a research network in which fish swimming in the wild and in aquaculture is studied for the first time under a multidisciplinary perspective. FITFISH will provide the ground for technological breakthroughs (e.g. more accurate monitoring of migrant fish; design of exercise-“friendly” fish farming facilities), for establishing swimming as an essential factor determining welfare and for demonstrating that swimming can benefit quality production. FITFISH will add value to independent, nationally funded research activities by providing the means to exchange information, promote industrial activities and influence policies at a European level in a new common forum. Activities in FITFISH also include the training and exchange of early stage researchers in the area. For more information: www.fitfish.eu.