105 Records

The Rainbow Darter (Etheostoma caeruleum) is a stunning freshwater species now found in the Piedmont region of Maryland. We currently have records for Allegany, Washington, Frederick, and Montgomery Counties. It is also found in the upper Susquehanna in Pennsylvania. Rainbow Darters are native to the Great Lakes and Mississippi River drainage. They were first collected in the Potomac River drainage in 1977 (Cessna et al, 2014). The species has apparently expanded rapidly in Maryland, Pennsylvania, Virginia, and West Virginia. The mechanism of this expansion isn't clear but some sources suggest likely human assistance.