The hardhead snailfish (Lopholiparis flerxi) is a species of marine ray-finned fish belonging to the family Liparidae, the snailfishes. This species is found in the northern Pacific Ocean where a single specimen (the holotype) was collected in June 2000 from near the Aleutian Islands at a depth of . The length of the fish was SL. This species is the only member of the monospecific genus Lopholiparis.[1] The specific name honors the collector of the holotype, William C. Flerx of the National Marine Fisheries Service.[2]