The Hawaiian chub was first formally described in 2004 by the Japanese marine biologists Keiichi Sakai and Tetsuji Nakabo with the type locality given as Kaupoa on Molokai Island in the Hawaiian Islands.

It is a similar bluish-gray basic color, but the Hawaiian chub darkens towards the tail, forming a distinct two-tone pattern.

The body is oval, deep and highly compressed with a terminal mouth containing incisor-like teeth.

It is found at depths of greater than 1 m (3 ft 3 in) in the vicinity of rocky and coral reefs within the intertidal and subtidal zone.

[4] The Hawaiian chub lives in small schools in the surge zone on the top of reefs and in dropoffs where it may be encountered in the same places over a number of years, suggesting that these schools are territorial.