OSMOSE is a multispecies and Individual-based model (IBM) which focuses on fish species. This model assumes opportunistic predation based on spatial co-occurrence and size suitability between a predator and its prey. It represents fish individuals grouped into schools, characterized by size, weight, age, taxonomy, and geographic location (2D model), that undergo the major processes of the fish life cycle (growth, reproduction, migration, and mortality from starvation, predation, and fishing). The model requires life history parameters which are often available for a wide range of species, e.g. in FishBase. All current Osmose applications are coupled with hydrodynamic and biogeochemical models that directly influence fish physiology and spatial distribution. Bioenergetic, evolutionary and economic modules are available from version 4.3.3. Output indicators are spatially, temporally, size, age and species resolved.