Flavobacterium psychrophilum and F. columnare cause high mortalities in salmonid culture as the cause of various surface and systemic infections. Traditionally, Flavobacterium infections have been treated with antibiotics, but this is an emotive issue because of the perceived problems associated with tissue residues and the development and spread of antibiotic-resistant bacteria. Indeed the high susceptibility of Flavobacterium for the antibiotics commonly used in EU fish farms has been recorded. Alternative methods of disease control are needed for which the use of bacteria as probiotics and/or water treatments is gaining attention. Thus, the role of the beneficial bacteria is to exclude pathogens and promote the good indigenous microbial flora in fish. The aim of this research is to optimize protective bacteria which work as biological control agents against Flavobacterium infections. The research will focus on three bacterial cultures which have been highlighted in preliminary in vitro and in vivo work by the researcher, to determine their mode of action for disease control in salmonid culture. As Flavobacterium usually affects the host through external surfaces, it is proposed to study how the beneficial bacteria exclude the pathogen from these surfaces. Furthermore, the role of bacterial subcellular components will be investigated by means of immunoproteomics. Although immunoproteomics is extensively used in vaccine production, their use here would lead to more precise information about the nature of similar or shared antigens between the protective bacteria and pathogenic Flavobacterium. Apart from enabling research on a topic of relevance to European aquaculture, this Fellowship would be greatly advantageous to the researcher’s career development, by the provision of training and a personalized research programme with high quality outputs in the laboratories of well known and respected academics in the Institute of Aquaculture at the University of Stirling.