Exastilithoxus is a small genus of suckermouth armored catfish native to South America.

[2] These species exhibit a round lower lip with fleshy barbels.

[2] Color pattern is generally mottled and dark brown with paler areas under and just posterior to the dorsal fin.

The abdomen is white, fins are mottled, and the ventral surface of the caudal peduncle is colored as the sides, but slightly lighter.

[2] Exastilithoxus species are unique among loricariids in that they subsist entirely on insect larvae.