Rainer Froese is the project leader and coordinator of FishBase, the largest and most widely used biological information system available on the web. He was one of the architects of FishBase, having been involved since its inception in 1990 at the International Center for Living Aquatic Resources Management (ICLARM) in Manila, Philippines. Previously, he worked on life history strategies of fish larvae and on computer-aided identification systems at IfM.

Fish are the largest group of vertebrates, with about 30,000 species, and interact with countless other species. Froese's research focuses on biodiversity and population dynamics of fishes with the goal of conservation and sustainable management in mind. He prefers data-rich approaches that emphasize commonalities rather than differences between species. He claims that the often-heard statement "Nothing is known about fish X" is usually not true because reasonable first estimates with error margins can be made for many life history traits if the maximum length and age at first maturity are known.

Getting the scientific names right is a precondition to any serious work in biodiversity.Froese therefore accepted in 1995 an invitation to join the Species 2000 Project Management Team, an initiative to establish an authoritative checklist of scientific names for all organisms on earth.

Froese considers the intelligent merging of available biological and environmental data as one of the main tasks of the new field of biodiversity. In 2001 he accepted an invitation to join an international committee to establish an Ocean Biogeographic Information System, which is intended to make use of the Internet by combining occurrence and abundance data for marine species with oceanographic data sets.