The Guardian Darter is found in tributaries to the lower Tennessee River Drainage in Tennessee and Kentucky. They live primarily in pools and riffles with slab-rock and gravel substrate. Like other members of the subgenus Catonotus, this species spawns on the underside of flat rocks. Males have round structures on the rays of their second dorsal fin that are hypothesized to serve as an “egg-mimic” to attract females for spawning. Their common name reflects the fact that males guard their nests.