Data associated with the manuscript "Niche conservatism and spread explain hybridization and introgression between native and invasive fish" by Jordan H. Hartman, Joel B. Corush, Eric R. Larson, Jeremy S. Tiemann, Philip Willink, and Mark A. Davis. For this project, we combined results of ecological niche models (ENMs) and next-generation restriction site-associated DNA sequencing (RADseq) to test theories of niche conservatism and biotic resistance on the success of invasion, hybridization, and extent of introgression between native Western Banded Killifish and non-native Eastern Banded Killifish. This dataset provides the sampling locations and number of Banded Killifish in each population, accession numbers for RADseq from the National Center for Biotechnology Information Sequence Read Archive and the assignment of each Banded Killifish, the habitat associations of each population from the ENMs, and the occurrence points used to build the ENMs.