Fish Facts » Mackerel
Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. Common features of mackerels are a slim, cylindrical shape (as opposed to the tunas which are deeper bodied) and numerous finlets on the dorsal and ventral sides behind the dorsal and anal fins. The scales are extremely small, if present.
Most live offshore in the oceanic environment but a few, like the Spanish mackerel (Scomberomorus maculatus), enter bays and can be caught near bridges and piers. Mackerels are prized (and are highly harvested) for their meat, which is often very oily. They are known for their fighting ability, and are an important recreational and commercial fishery. The meat can spoil quickly, especially in the tropics, causing scombroid food poisoning - it must be eaten on the day of capture, unless cured. For this reason, mackerel is the only common salt-cured sushi.
The largest species called "mackerel" is the king mackerel (Scomberomorus cavalla) which can grow to 66 inches (1.68 m).
They occur in all tropical and temperate seas.
Source(s) on the web