There is a real need today to train experts in the whole process of fish immunity with a comprehensive understanding of how such an expertise could be beneficiary for both food production in fish farming and for human health. With this aim in mind, we propose to train 15 promising young scientists, through a combination of individual research projects, collaborative efforts and coordinated training, thereby providing a strong theoretical / knowledgebase and competencies in relevant laboratory-based techniques. The research objectives of the training are the following: • Understand the genomic, cellular and developmental basis of the fish immune system • Understand the diversity of immune strategies in different groups of fish, either of aquaculture importance or of easy manipulations in the laboratory. Note that the diversity of farmed fish species is still increasing and is much higher than for all other groups of farm/domestic animals. Efficient and cheaper vaccination remains a key priority for sustainable development of fish farming, in particular to limit the use of antibiotics as much as possible. • Develop new in vivo imaging strategies in fish models, not only to describe the behaviour of fishs, the behaviours of the cellular actors of immunity, but also to dissect the molecular basis of immunity to the main infections affecting fish aquaculture, and to propose new fish models to study human infectious diseases. • Develop original mathematical and modelling tools, to analyse both the wealth of data generated, and to inform the development of models with which to understand immune processes, and tools to understand the pathological basis of human infectious diseases This training frame is by design interdisciplinary, involving scientists from very different fields of biology (structural biologists, imagers, immunologists, geneticists), as well as mathematicians, programmers and modellers. We have made a particular effort to ensure that the proposed training frame be intersectorial, to maximise the possibility that the spin-offs of such a scientific program will reach the patient through the fostering of dedicated business enterprise initiatives. The programme will involve both technical training, so that all recruited PhD students reach a common level of expertise allowing real interdisciplinary collaborations, and complementary / transferable skills enabling the development of successful scientific careers - in both the academic and industry spheres. Importantly, recruited PhD students will also be trained to communicate their work, not only to their peers, but also to the general public, since we recognised the critical importance of informing and raising the scientific awareness of the general public. This will be achieved through scientific articles, communication and outreach events, Wikipedia articles, a MOOC and serious games. To our knowledge, this is the first European network set to meet the challenges outlined here, and we believe that the proposed programme will contribute to the training of future European leaders in this interdisciplinary field.