Endemics result from several natural processes. Often, these fish require such precise environmental conditions that they can only survive in specific locations. Other endemics may have only recently evolved and, therefore, have limited ranges that are slowly expanding. Most endemics were once widespread but, due to environmental changes or pollution, now survive in small areas of their remaining habitat.

Lake Waccamaw in Columbus County in southeastern North Carolina is home to three endemics --the Waccamaw silverside, Waccamaw killifish, and Waccamaw darter. The Waccamaw darter is confined to Lake Waccamaw and the headwaters of the Waccamaw River. The silverside is restricted to Lake Waccamaw. The Waccamaw killifish was also recently found in Lake Phelps in Washington and Tyrrell counties in northeastern North Carolina, where it was probably introduced through its use as fishing bait. 

The Cape Fear drainage area in the central portion of the state, near the Fall Zone in Chatham and Harnett counties, is home to the Cape Fear shiner. The Pinewoods shiner and the Carolina madtom are restricted to the piedmont and coastal plain regions of North Carolina, in the Neuse and Tar River drainages.

Approximately 25 species of fish have ranges restricted to North Carolina or to drainage areas shared by bordering states. All freshwater fish are vulnerable to water pollution, but because of their limited range and distribution, endemics are particularly at risk. That is why five of North Carolina's six endemics are listed as threatened, endangered, or of special concern.