Filter-feeds with its mouth held open, and passes over muck sites in schools of thousands.
To about 35 cm, slender and streamlined, blue-green above and silver below with rows of small dark spots along the upper flank and a golden band along the side. Two widely separated dorsal fins and a series of small finlets before the tail place it as a mackerel at a glance.
It feeds on zooplankton and phytoplankton by swimming with the mouth wide open and the gill covers flared, filtering through long gill rakers; a school doing this passes as a wall of open mouths and is unmistakable. Schools of hundreds to many thousands move through inshore water including over muck sites, usually in the upper part of the water column, and are a major commercial fishery throughout the region. Encounters are unpredictable and brief. Recorded from the surface to about 30 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.