Chlamydia trachomatis is a devastating human pathogen, causing blindness, infertility and systemic disease; related Chlamydia bacteria cause respiratory infections and pre-term abortions in other vertebrates. These bacteria all have an intricate intracellular lifecycle. Recent in depth genomic studies on Chlamydia trachomatis have provided insights into how this species uses recombination to increase its potential for diversity. Recent studies in fish, both wild and farmed, have discovered new, related pathogens within the phylum Chlamydiae. The presence of these infectious bacteria impacts on the health of fish in aquaculture, which is a growing industry of key importance for meeting global food demands. Further studies into these emerging pathogens are required. We propose to perform large scale genomic analyses similar to those used with other Chlamydia species, using novel bacterial isolation technologies and high throughput sequencing. We aim to characterise selected strains using state of the art proteomics and metabolomics technologies. We also aim to develop methods for growing these currently uncultured bacteria, to allow further investigations in vitro. These aims can only be achieved through a combination of the expertise of the researcher, and the technology and background knowledge of the host institution. The researcher brings genomic experience, and a newly developed bacterial isolation technique, and will receive training in novel methodologies to complement existing skills. Both the researcher and host will provide collaborations for the project, including new intra-European and global contacts. Through this process we aim to get a greater insight into the evolution and diversity of these fascinating intracellular bacteria, to learn more about their infection of fish with a view to reducing disease burden, and to build a basis upon which we can begin to define diagnostic and treatment targets to benefit the European aquaculture industry.