Horse mackerel (Trachurus trachurus) is a fish species of the family Carangidae . It is a pelagic species and can be found in the Atlantic Ocean and the Mediterranean Sea. The horse mackerel is distinguished by a very indented caudal fin and bony scutes (in the posterior lateral line), highlighting its silvery sheen. It stays in coastal waters for its first two years, then moves to the continental shelf. It does not return to the coast until adulthood, during its summer migration. The male becomes sexually mature at 3 years old, when it measures approximately 20-22 cm, while the female reaches sexual maturity at 4 years old, when it measures 26-30 cm. The horse mackerel can live up to 15 years. Like all other small pelagic fish, horse mackerel populations are sensitive to environmental changes.