The Checklist of non-native freshwater fishes in Flanders, Belgium is a species checklist dataset published by the Research Institute for Nature and Forest (INBO). It contains information on 34 non-native fish species occurring in Flemish natural and semi-natural waterbodies, detected in sampling between 1992 and 2024. This species checklist was assessed within the framework of the Freshwater Fish Monitoring Network by Verreycken et al. (2007) and reassessed for Verreycken et al. (2024). Here it is published as a standardized Darwin Core Archive and includes for each species: the scientific name, kingdom, and stable taxon identifier (in the taxon core), the Dutch and English vernacular name (in the vernacular names extension), the year of first introduction and last assessment in Flanders (given as a year range in the event date in the distribution extension), coarse habitat information (in the species profile extension) and the pathway(s) of introduction, native range(s), and invasion stage in Flanders (in ...