The molly miller is a marine tropical fish that lives in rocks or coral reefs 0–10 m below the surface.

The molly miller was first formally described as Blennius cristatus by Linnaeus in the 10th edition of Systema Naturae with its type locality given as Ascension Island.

[4] The Brazilian clades are sympatric from Rio de Janeiro to Rio Grande do Sul states (southern Brazil), with one clade being unique to Brazil and the other closely related to the eastern Atlantic lineage.

The fish can be found in the southern Mediterranean, including near Milan, Sicily, and the Peloponnese (Greece).

[1] Records from the western Pacific are regarded as doubtful and may refer to the maned blenny (Scartella emarginata).