Forty-one species of fish have been recorded in park waters. The mountain streams of the park are one of the last completely protected strongholds of the native eastern brook trout (Salvinus fontinalis). Of the approximately 90 small streams in the park, most contain brook trout. The cool forested slopes give rise to clear cold waters thus providing excellent habitat for this species. Other common species known to occur in the park include the blacknose and longnose dace, the mottled sculpin, the bluehead chub, and the fantail darter.
Monitoring efforts by park staff have revealed interesting facts about park fish. For instance, in 1998, greenside darters were found in park waters. This was unusual because the species in Virginia was split into two distinct populations. One population is found in the southwestern counties of the state and the other in the Potomac watershed. This later population is suspected to have been introduced.
We can only speculate about what influence the presence of fish had on the selection of this portion of the Blue Ridge Mountains as a national park. We know that many of the people who were influential in this selection were ardent trout anglers. President Hoover established his camp on the Rapidan River as both a retreat to ease the pressures of political life and as a location with ready access to excellent fishing. Fishing and fish observation continue to be recreational activities enjoyed by thousands today.