National Park Service The Upper Delaware River and its tributaries support a diverse array of fish species. The river’s consistently high water quality provides critical habitat for a variety of fish species from many different families. The Delaware River is unique among large eastern rivers because it remains undammed throughout the length of its mainstem. This has allowed the mainstem and at least portions of some tributaries to maintain a natural connection to the Atlantic Ocean. This connection without barriers blocking their passage means that migratory fishes can still reach the Upper Delaware River. Although the mainstem remains undammed, dams on its two major branches have created a year-round coldwater system that extends into the upper portions of the mainstem. Downstream of the coldwater influence the river becomes more of a warmwater system. All of these factors contribute to the diversity of fishes found in the Upper Delaware River. The following list is not comprehensive but instead provides an overview of some of the most ecologically and recreationally important species in the Upper Delaware River. The Northern Snakehead is an invasive fish species found in the Upper Delaware River but not included in the list below. To learn more about the Northern Snakehead, visit the Common Nonnative Aquatic Species page. 
Coldwater Fish Species
Learn about the Coldwater Fish Species found in the Upper Delaware River. 
Migratory Fish Species
Learn about the Migratory Fish Species found in the Upper Delaware River. 
Other Gamefish Species
Learn about the Gamefish Species of the Upper Delaware River. 
Nongame Fish Species
Learn about the Nongame Fish Species found in the Upper Delaware River. |
Last updated: January 21, 2021