Good resource management is ultimately the ability to maintain the health of exploited ecosystems, ensuring that their potential for biological productivity is maintained and its vulnerability to external factors is minimised. When assessing ecosystem health, biodiversity is only one aspect to be considered. However, changes in the biodiversity of exploited ecosystems over time might help to indicate whether their productivity and resilience are optimal. For this, as well as for assessing the status of species and populations and picking up warning signals where those are under threat biodiversity must be documented in an appropriate format Froese (1996) suggested that a 'unit' of biodiversity information must include four core elements: species name, date, source, and locality. FishBase, a global database on the biology and ecology of finfish built through international collaboration and sharing of data has used this and other approaches to develop tools for biodiversity studies. Cooperation with European museums has enabled the numerous occurrence records in their fish collections to become progressively available in FishBase. Linked to the authoritative database on fish taxonomy in FishBase, such records facilitate investigations into the status (occurrence and distribution) of a species over time, irrespective of changes in nomenclature. Other links within FishBase permit retrieval of information on the biology and ecology of a given species, its use and status of threat. Overall, while not a substitute for on-the-spot surveys of current status, these tools give added value to existing data and can identify trends and potential threats and problems that might not be obvious from narrower, one time studies. FishBase has routines to explore biodiversity data including, among others: national fish checklists; occurrence records; biodiversity maps; introductions; trophic ecology; parameters in ecosystem modelling with Ecopath; and key facts. The key facts are summary sheets of important biological parameters allowing, for example, analysis and comparison of representative length-frequency data sets of a given stock or population against generalised length-based indicators for that species (e.g. length at first maturity, optimum capture length, asymptotic length). The results facilitate rapid assessment of the status of an exploited fish population. FishBase remains under continuous development so as to improve its coverage of all known finfish species and its utility as a tool for fish biodiversity assessment and management. All the data and tools in FishBase are under common ownership and are becoming available through the Internet. All concerned with the development of FishBase welcome additional collaborators as well as critical feedback from its users.