Margined Madtom lives in the lower reaches of streams with rocks and moderate current. The three Atlantic slope watersheds where it is native are in the southeast and south central, while it has become established in 11 other watersheds, or in all but Erie, Allegheny, Champlain and Long Island. There are no recent records from Genesee since 1970, so it may have failed to become established there. Field identifications have sometimes been cursory, and its possible replacement or displacement of stonecat has gone unnoticed. Range expansion and increase in frequency occurrence have been substantial.