Fish occurrence data to support high-resolution distribution models and test various community and macroecological hypotheses have not been available at the national scale. We present IchthyMaps, a database of high-quality historical fish occurrences covering fishes of the conterminous United States. Designed on the principles of metacommunity ecology, IchthyMaps is a compilation of presence records from atlases up to 1990, at the resolution of the 1:100,000 National Hydrography Database Plus (NHDPlus) inter-confluence stream segment, readily aggregated into hierarchically coarser units (e.g. hydrologic unit code 8-digit and 12-digit watersheds). IchthyMaps contains about 606,550 presence records for 1,038 species and subspecies. These presence records occurred on 224,305 NHDPlus interconfluence stream segments, representing > 10% average sampling intensity. IchthyMaps is publicly accessible through USGS' ScienceBase infrastructure. It offers unprecedented opportunities for both basic and applied research and conservation initiatives in areas such as studying biogeography, gap analysis, and assessments of impacts of land use, species invasions, and climate change. More generally, this database broadens our capability to conduct research on fish ecology, biogeography, and management.