Despite extensive research in the past ICES scientist are currently not able to conclusively explain the ecological interrelationships which drive the current changes in the eastern Baltic cod stock. Equation-based macro-models do not deliver useful insights since they are not able to adequately depict the underlying physiological processes of cod. Therefore the aim of this project is the development of an agent-based multi-level model of the bioenergetics and behaviour of cod as well as of the hydrography of the Bornholm-Basin and the relevant aspects of its prey. Ultimately, the model developed in this project shall serve scientists from the fields of fishery biology and fish physiology as a simulation tool for academic research.