[4] Sebastes semicinctus is a relatively slender-bodied rockfish, its body's depth being between a aquarter and a third of its standard length.

The head is long and has a short snout, extremely large eyes and a quite small terminally positioned mouth.

[6] They are zooplankton feeders and their prey includes amphipods, copepods, crustacean larva, and krill.

[5] Like other rockfishes in the genus Sebastes this species is ovoviviparous, the females give birth to a single brood of larvae each year.

Each female can bear from 3,400 to just under 31,000 ooctyes which are fertlised internally in early winter with the eyed larvae being extruded in the following spring.