Mackerel have a very slender body with two separate dorsal fins, with short pectoral fins, and one anal fin followed by seven finlets. Its coloration is dark blue, with a white belly. It measures between 25 and 45 cm in length and can reach 4.5 kg in weight.
Characteristic of mackerel is its bright green back with undulating black bands that extend halfway up the animal’s flank. The belly and half of the flank are silvery white. The caudal fin is normally sickle-shaped.
There have been cases of mackerel with a length of 60 cm.