Fish
Jack
Carangidae · also called jacks, trevallies
A jack is built for one thing above all else: speed sustained over distance, a streamlined body and deeply forked tail powering some of the strongest, most sought-after fights any angler can hook into. Many species hunt in coordinated groups too, herding smaller fish into a tight, panicked ball before picking them off one by one.
Overview
Jacks, family Carangidae, are an enormous, diverse family of fast, powerfully built predators found in tropical and temperate seas worldwide, from shallow reefs to open ocean. Streamlined bodies and forked tails support sustained high-speed pursuit of schooling prey, often coordinated in groups.
Built for the fight, and the fishery
That same speed and endurance make jacks prized game fish, known for a strong, sustained fight once hooked, while numerous species also support significant commercial fisheries worldwide as valued food fish.
Status
Least Concern collectively — widespread and abundant across most of the family, though individual species can face notable regional fishing pressure.
Jack: common questions
Why are jacks considered such strong fighters when caught fishing?
A jack's body is built almost entirely around sustained, powerful open-water swimming, with fast-twitch muscle and a streamlined, deeply forked-tail design that maximises both speed and endurance, and these same physical traits translate directly into a strong, sustained fight when the fish is hooked, making jacks notably challenging and rewarding targets for anglers compared with many less powerfully built fish species.
How many different species belong to the jack family?
The jack family, Carangidae, contains well over 100 recognised species distributed across tropical and temperate seas worldwide, ranging from smaller inshore species to large, powerful open-ocean predators, and the family also includes fish more commonly known under other specific names, such as pompano and amberjack, reflecting its considerable internal diversity.
Why do jacks sometimes hunt in coordinated groups?
Hunting cooperatively allows a group of jacks to herd and concentrate smaller schooling prey fish into a tight, disoriented ball, often near the surface or against a natural barrier such as a reef or shoreline, making it considerably easier for individual jacks within the group to then pick off prey from the confused, densely packed school than hunting alone would allow.
What are scutes and why do some jacks have them?
Scutes are hardened, plate-like scales found in a row along part of the body near the tail in a number of jack species, providing some additional structural reinforcement in a fast-swimming, open-water fish that experiences considerable mechanical stress on its body during rapid, sustained swimming, and this scute row is one of several physical adaptations across the family linked to a highly active, speed-focused lifestyle.