The Blackmouth Shiner is restricted to three Gulf Coast drainages from Mississippi to Florida, including one tributary to Mobile Bay in Alabama. They are found in tannic, or tea-colored, waters of swamps, oxbow lakes, and sloughs with abundant aquatic vegetation. As the common name suggests, the inside of the mouth of Blackmouth Shiners is lined with black pigment. It is one of the smaller species in its genus, reaching a maximum size of 1.5 inches.