The banded killifish (Fundulus diaphanus) is a North American species of temperate freshwater killifish belonging to the Fundulus genus of the Fundulidae family. The natural geographic range extends from Newfoundland to South Carolina, and west to Minnesota. It includes the Great Lakes drainages. The banded killifish is the only freshwater killifish found in the northeastern United States. While it is primarily a freshwater species, it can occasionally be found in brackish water.