Description: American Brook Lamprey has characteristics which are eel-like, as well as no jaw, teeth moderately developed in adults, and a sucking disk. The first and second dorsal fins are separate with lateral pores un-pigmented. The dorsal fin is divided into two lobes—the posterior is continuous with the caudal fin and the anterior is separate. The coloration is brownish to light gray or silver (adults only) on dorsal surface and flanks, grading to light gray/brown, olive or off-white. The typical length of an average adult is around 130-165 mm.
Habitat: This species prefers cool, often spring-fed streams, ranging from small to medium size with clear water. Stream beds are sometimes made up of sand or small-sized gravel.