The Blue Assessor is also called the Blue Devilfish, but other small blue fish also have that name. It is native to reefs of the southwestern Pacific around the Great Barrier Reef and from northeastern Australia/New Guinea to New Caledonia. Assessors, all three species, have long, flowing fins, especially long pelvic fins, grow to 6cm long and often swim upsidedown.

The Randall's Assessor, also called Randall's Devilfish, is native to reefs around Japan and Taiwan. Females can become males and vice versa. It can be a brighter blue than the Blue Assessor, especially the males which develop orange markings when mature; they can be a mauvish colour with purplish, but always rounder, fin tips. Habits are similar and, as with all three species of assessor, the males are mouthbrooders.