Juveniles or ammocoetes are found in slow moving water buried in soft substrate of medium to large streams.

[5] The mountain brook lamprey has a fragmented range in the Mississippi basin with populations being found in New York, Pennsylvania and adjacent areas of Ohio.

The mountain brook lamprey is found in gravel riffles and sandy runs of clean, clear streams and in the sand, mud and debris in pools and backwaters.

[5] The general view is that lampreys do not feed during metamorphosis with the loss of body energy reserves being countered by water uptake.

[6][7] However, in the case of I. greeleyi, it is reasonable to assume metamorphosing animals do not feed but maintain body size by water uptake.

By the completion of metamorphosis body water content increased to 79.4 rt 3.7% (n = 6), a value almost identical to that predicted from the earlier metabolic studies.

The males build nests just above riffles in about 1 foot of water, and just downstream from a flat stone 6 to 12 inches (15 to 30 cm) in diameter.

[11] Coloration of live mountain brook lamprey did not change between the ammocoete and senescent periods and ranged from butterscotch to olive brown.