Fish

Mackerel

Scomber and relatives · also called mackerels

Not Evaluated carnivore Ocean Coasts & shorelines

A mackerel is a tuna in miniature — the same stiff torpedo body, the same row of little finlets ahead of a forked tail, the same commitment to swimming fast and more or less non-stop. It travels the coasts in schools of millions, it is one of the most nutritious fish a person can eat, and it is caught by the million tonnes.

Overview

Mackerel are small, fast members of the family Scombridae, the tuna and bonito family. The true mackerels are the genus Scomber (Atlantic, Pacific, chub) and the Indian mackerels Rastrelliger, with the larger king and Spanish mackerels in another genus. All live in the open water of continental shelves in temperate and tropical seas, and all are carnivores, taking plankton, fish eggs, and small schooling fish.

Built like a tuna

Mackerel share the scombrid design — a rigid spindle body, finlets smoothing the water flow to the tail, a deeply forked tail, and fins that fold into grooves — all for efficient sustained swimming. The Atlantic mackerel’s wavy dark bars on a blue-green back give it camouflage from above and below.

Schools and seasons

Mackerel form dense schools of thousands to millions that turn as one, and they migrate inshore and toward the surface to feed in warm months, then offshore and deep to overwinter. They grow fast, breed young, and are hugely productive, so stocks rebuild quickly — but also swing widely with ocean conditions.

Food

Mackerel flesh is dark and oily, one of the richest sources of long-chain omega-3 fats, plus vitamin D and B12. The small species are low in mercury; king mackerel is high and is on the avoid list for pregnant people. Mackerel also spoils fast, producing histamine that causes scombroid poisoning if it is not iced immediately.

Status

Mackerel as a group are Not Evaluated. The Northeast Atlantic stock is large but caught above scientific advice because the countries that share it cannot agree on quota shares, and several other mackerel stocks are fished near or above sustainable limits.

Mackerel: common questions

Is a mackerel a type of tuna?

They are close relatives in the same family, Scombridae, and a mackerel is in effect a small, slender member of that family, but the fish specifically called mackerels are their own genera, chiefly Scomber for the true mackerels and Rastrelliger for the Indian mackerels, distinct from the tuna genera such as Thunnus. The larger fish called king mackerel and Spanish mackerel are in yet another genus, Scomberomorus, and sit between the small mackerels and the tunas in size and lifestyle. All share the scombrid body plan of a stiff spindle, finlets, and a forked tail built for sustained swimming, and unlike most true tunas, small mackerels are not warm-blooded.

Why is mackerel considered so healthy, and are there any cautions?

Mackerel is an oily fish, meaning the fat is spread through the flesh rather than concentrated in the liver, and that fat is unusually rich in the long-chain omega-3 fatty acids EPA and DHA, which are linked to heart and brain health. It also supplies plenty of vitamin D, vitamin B12, selenium, and protein. The main caution concerns the largest species. King mackerel accumulates high levels of mercury and is on the list of fish that pregnant people and young children are advised to avoid, whereas the small Atlantic and chub mackerels and canned mackerel are low in mercury and are recommended as a good regular choice.

Why does mackerel spoil so quickly?

Mackerel has dark, oily, blood-rich muscle and a high level of the compound histidine, and after death enzymes and bacteria rapidly convert histidine to histamine and other amines. If the fish is not chilled fast and kept cold, histamine builds up to levels that can cause scombroid poisoning, an illness with flushing, headache, rash, and stomach upset that comes on within an hour of eating and resembles an allergic reaction. Cooking does not destroy the histamine once it has formed. This is why mackerel and other scombrids are gutted and iced immediately on catching and why very fresh or properly frozen fish is important.

What is the mackerel quota dispute about?

The Northeast Atlantic mackerel is one shared fish stock that migrates through the waters of several countries and international areas around the North Atlantic. Historically the European Union, Norway, and the Faroe Islands agreed catch shares, but as the stock shifted its distribution northward and westward, Iceland and later Greenland began taking large catches too, and the parties have been unable to agree on how to divide the total. As a result each side sets its own quota, and the combined catch has for years exceeded the level scientists advise, so a large and currently reasonably healthy stock is being fished harder than its own managers say is safe.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Scomber and relatives
Diet: Small planktonic animals such as copepods and other crustaceans, fish eggs and larvae, and small schooling fish such as sand eels, sprat, and young herring, taken by active pursuit and, when plankton is dense, by swimming with the mouth open to filter it through the gill rakers
A small tuna, essentially: Mackerel belong to the family Scombridae alongside the tunas and bonitos, sharing the stiff spindle body, the row of small finlets between the last fins and the tail, the deeply forked tail, and fins that fold into grooves to cut drag, all adaptations for fast, efficient, more or less constant swimming
Iridescent wavy stripes: The Atlantic mackerel has a metallic blue-green back marked with dark wavy bars and a silvery belly, a pattern that from above blends with the dappled sea surface and from below is hard to see against the bright sky, giving the fish camouflage from predators approaching from either direction
They school by the million: Mackerel form dense schools of thousands to millions of similarly sized fish that move and turn as one, which confuses predators, and the schools migrate seasonally, moving inshore and toward the surface in warmer months to feed and offshore into deeper water to overwinter
Fast growing, short lived, hugely productive: Mackerel mature within a couple of years, and a female releases hundreds of thousands of eggs in batches over a long spawning season, so populations can rebuild quickly, though they also swing widely from year to year with ocean conditions
An oily fish rich in omega-3: Mackerel flesh is dark and high in fat, which makes it one of the richest dietary sources of long-chain omega-3 fatty acids along with vitamin D and B12, and it is eaten fresh, smoked, salted, and canned across Europe, Asia, and beyond
The catch is enormous: Several mackerel species are among the most-landed fish in the world by weight, with the Atlantic mackerel, the Indian mackerel, and the chub mackerels each supporting fisheries of hundreds of thousands to millions of tonnes a year
Range: The temperate and tropical waters of the Atlantic, Pacific, and Indian oceans and the Mediterranean and Black seas, in the open water of continental shelves and the upper open ocean, usually within a few hundred kilometres of coasts, with strong seasonal migrations between feeding and overwintering areas and, in the tropics, more localised movements.
Conservation status: Not Evaluated ≈ Not assessed as a group, and status varies by stock, with the Northeast Atlantic mackerel stock large but the subject of a long-running international dispute over quota shares that has kept total catches above scientific advice, the Atlantic chub mackerel and Indian mackerel generally fished near or above sustainable limits in places, and the larger relatives such as the king and Spanish mackerels managed as separate coastal stocks with mixed results in the wild