Juvenile mountain madtoms are 20-30mm in length usually. Adult mountain madtoms range from 75–127 mm in length and the life span averages 4–5 years. It is uncertain what age they reach sexual maturity due to the secrecy of the species. One study located a nest and eggs were collected. In the study the nest was found in a moderately flowing stream, in a clean swept gravel substrate under a rock, 20m above a riffle. A male mountain madtom was seen guarding the nest. The estimated clutch size is 55-115 eggs per female Relative to other fish the mountain madtom has a small clutch size because they do provide a lot of parental care to the young. The breeding season was determined to be June–July, based on the time the nest was found and how developed the eggs were. Human activity that puts silt in the streams can cause the eggs to suffocate which is detrimental to the population. The ideal temperature for the eggs to hatch is 24 C.
