Biogeographia – The Journal of Integrative Biogeography

Mediterranean inland and transitional waters are fragile ecosystems currently facing rapid biodiversity loss due to anthropogenic pressures and climate change. In Sicily, the largest island in the Mediterranean Sea, knowledge of ichthyofaunal assemblages of these ecosystems has remained fragmented, sporadic, and largely confined to "grey" literature for long. The present paper presents a dataset built with the aim to fill this gap. The dataset aggregates 808 occurrence records from 108 water bodies and localities, spanning a 50-year period (1976–2025). Data were recovered from diverse sources, including scientific literature, administrative reports, and conference proceedings, integrated with new unpublished data from recent field monitoring campaigns conducted by ARPA Sicilia following WFD (2000/60/EC) standards. Additionally, other unpublished data from direct information, interviews with local fishermen and acquisition of photographic records directly provided by citizens, were incorporated. The dataset is published on the GBIF platform. It is organized following to the Darwin Core (DwC) standards, in accordance with the FAIR (Findability, Accessibility, Interoperability, and Reusability) Principles. All records were georeferenced using WGS84 coordinates, validated via QGIS, and taxonomically updated according to the World Register of Marine Species (WoRMS) and the Catalogue of Life. The dataset covers 90 species across 26 orders and 41 families, and 68 genera, while the investigated area documents a wide range of habitats, from natural rivers and coastal lagoons to artificial reservoirs and saltworks. The records reveal a research effort geographically asymmetric, with 75% of occurrences concentrated in the eastern portion of the island.