The mackerel, measuring 25-30 cm, is a typical blue fish and an omnivorous, streamlined pelagic predator that lives in large shoals. Its colouring ranges from greenish-blue with metallic tones on the back to greyish-silver on the underside, with narrow black, tiger-like stripes running vertically from the back to just below the lateral line. The second dorsal fin is separate from the first and five small adipose fins are present between the second dorsal fin and the caudal fin. The tail is heavily forked. This species is present in many parts of the world, including the Mediterranean, where it prefers waters up to 200 m deep, which it leaves in huge shoals to make for coastal waters during the warmest times of the year (May-July), when it reproduces. It is an unfussy feeder, eating plankton, jellyfish, small fish, fish eggs and larvae, shrimps, worms and gastropod molluscs. Unusual anatomical features include gills that are never pink, but always grey, and the absence of a swim bladder, which is not noticeable when the fish is bought. Mackerels are caught with fishing lines, gillnets, surrounding nets and trawl nets. In the Upper Adriatic it is typically fished using lamps and surrounding nets. Minimum size 18 cm.