It is found in the western Pacific Ocean, mainly in the seas around Japan and Taiwan.

[1] It is a similar species to Assessor macneilli but it is slightly brighter in colour and has more rounded rounder fins which have with yellow markings, there are also yellow markings on its body.

[1] They are associated with crevices and gullies in reefs, where they hover at the entrances to caves and holes.

They are mouthbrooders, the male guards the eggs by keeping them in his mouth until they hatch.

[3] The specific name honours the ichthyologist John Ernest Randall of the Bishop Museum in Honolulu, who collected the type specimen.