The yellowtail rockfish (Sebastes flavidus), or yellowtail seaperch, is a species of marine ray-finned fish belonging to the subfamily Sebastinae, the rockfishes, part of the family Scorpaenidae. This species lives mainly off the coast of western North America from California to Alaska. The yellowtail rock fish has an elongate and compressed body which has a depth of around one-third of its of standard length. The head is comparatively short with a small mouth, positioned terminally and large eyes. It does not have robust spines on the head and those present are only the nasal spines while the preocular and parietal spines are typically absent and the supraocular, postocular, tympanic, coronal and nuchal spines are always absent. There are 13 spines and 14-16 soft rays in the dorsal fin and 3 spines and 7-9 soft rays in the anal fin. There may be an obvious knob on the symphysis of the lower jaw. This species attains a maximumtotal length of 66 cm (26 in) and a maximum total weight of 2.5 kg (5.5 lb). The overall color of the body is dark brown or greenish-brown with some of pale or bright white blotches immediately underneath the dorsal fins, fading to white below the lateral line. The caudal fin is vivid yellow and the rest of the fins are dusky yellow. The body darkens and becomes uniformly olive green and the blotches fade following capture although some reddish-brown speckling is often still present on the rear margin of each scale. The yellowtail rockfish occurs from San Quintin, Baja California, to Kodiak Island, Alaska. This species commonly occurs over deep reefs from the surface to depths of 549 m (1,801 ft). The juveniles are often found around floats and pilings.
