Horse-eye Jack

SizeUnknown

LifespanUp to 13 years

StatusNot Evaluated

About

Horse-eye Jack

The horse-eye jack (Caranx latus), also known as the big-eye jack or false jack, is a predatory pelagic fish belonging to the jack family, Carangidae. First described by Swiss naturalist Louis Agassiz in 1831 from Brazilian waters, the species derives its common epithet from its unusually large, expressive eyes. It is an active inhabitant of warm Atlantic waters, where it forms impressive schools over shallow to moderately deep marine habitats. Visually, the horse-eye jack closely resembles other large carangid species, possessing a moderately compressed, elongate body with a strongly curved dorsal profile. However, its head is visibly less blunt than that of the crevalle jack (Caranx hippos). Adult horse-eye jacks display a metallic coloration, ranging from dark blue or silvery-blue along the back to silvery-white or golden shades across the belly. Key diagnostic features for divers include a vibrant yellow to dusky tail fin, a completely scaled chest, and 32 to 39 dark, bone-like scutes guarding the caudal peduncle. Notably, this species lacks the distinct dark spot on the pectoral fin base seen in crevalle jacks, although a small spot may occasionally appear on the gill cover. Juveniles carry five dark vertical bands across their flanks, which fade as they mature. While they can reach a maximum length of 101 cm and a weight of 13.4 kg, most individuals encountered by divers measure under 60 cm. In the water, horse-eye jacks are gregarious, pelagic schoolers. They often congregate in tight formations, either exclusively among their own species or mixed with crevalle jacks. Fascinatingly, individual jacks have also been documented swimming in coordinated pairs with unrelated species, such as the puddingwife wrasse (Halichoeres radiatus). Their oversized eyes are covered by a protective adipose eyelid, providing acute vision in dim or turbid conditions. The Horse-eye Jack, Caranx latus, typically exhibits schooling behaviour as juveniles, forming large aggregations in coastal waters and estuaries, before becoming more solitary or forming smaller groups as adults, often found around reefs and wrecks. They are primarily diurnal, actively foraging for smaller fish and invertebrates during daylight hours. Regarding reproduction, this species is oviparous and employs broadcast spawning, releasing eggs and sperm into the water column for external fertilisation. Spawning generally occurs offshore, with peak activity documented during warmer months in specific regions, such as late spring to early autumn in the western North Atlantic. Specific clutch sizes and incubation periods are not precisely quantified in broad literature, but the transparent, pelagic eggs typically hatch within a day or two. Larvae are pelagic before developing into juveniles that often seek shelter in inshore nurseries. Sexual maturity is reached at around two to three years of age, or at a length of approximately 30-40 cm. For scuba divers, these fish offer dynamic encounters. While they often maintain a cautious distance and slowly move away from sudden movements, their innate curiosity frequently leads them to circle stationary divers or follow large sea creatures, possibly mistaking them for food sources or protective cover.

Size

Unknown

Weight

Up to 13.4 kg

Lifespan

Up to 13 years

Status

Not Evaluated

Where to Find Them

Best Diving Locations

Diving Tips

Scuba divers frequently encounter horse-eye jacks along offshore reef drop-offs, wrecks, and around submerged structures such as oil platforms. Because these pelagic fish are naturally cautious, approaching them directly or making sudden, aggressive movements usually causes the school to drift slowly out of range. To achieve close passes, divers should maintain neutral buoyancy, move calmly, and remain relatively stationary. Horse-eye jacks possess a curious nature and will often swim over to investigate divers who stay quiet in the water column. When hovering near reef edges or structure walls, divers may find themselves enclosed by spiralling schools of silvery jacks. Watching their approach from slightly below against the surface light provides excellent photographic opportunities, highlighting their yellow tail fins and large, reflective eyes. Because horse-eye jacks typically inhabit depth ranges between the surface and 20 metres (although capable of descending down to 140 metres), divers can enjoy prolonged, shallow safety-stop encounters with them. Always maintain good trim to avoid disturbing sandy or muddy substrate near shallow reef boundaries where juveniles or hunting adults may be present.

Best Season

Horse-eye jacks can be encountered year-round throughout their warm subtropical and tropical Atlantic range. Across Caribbean destinations, the Gulf of Mexico, Bermuda, and off the coast of Brazil down to Rio de Janeiro, resident populations remain present on offshore reefs, shallow banks, and oil platforms throughout all twelve months. Spawning activity has been specifically documented during the summer months of June, July, and August off Cuba. During this summer reproductive season, schooling behaviour around island shelves and deep reef margins can become particularly dense as mature adults gather for dioecious spawning and external fertilization. In peripheral regions of their northern distribution, such as the eastern coast of the United States up to New Jersey, sightings peak during the warmer summer and early autumn months when water temperatures rise. In the eastern Atlantic, including oceanic outposts like Ascension Island and St Paul's Rocks, sightings depend heavily on local water conditions, though populations are considered year-round residents in these isolated tropical waters.

Habitat

The horse-eye jack is primarily a pelagic species occupying subtropical and tropical marine environments across the Atlantic Ocean. In the western Atlantic, its range spans from New Jersey in the northern United States, Bermuda, and the northern Gulf of Mexico southward through the entire Caribbean Sea to Rio de Janeiro, Brazil. In the eastern Atlantic, the species is found around Ascension Island, St Paul's Rocks, and occasionally within the Gulf of Guinea. Adult horse-eye jacks inhabit offshore coral and rocky reefs, open water, and artificial structures like oil rigs, ranging from surface waters down to depths of 140 metres. However, they are most frequently observed by divers in shallow to upper-slope reef zones between 0 and 20 metres. Juveniles favour inshore coastal habitats, including sandy beaches and muddy bottoms. They demonstrate a high tolerance for varying salinity, frequently penetrating into brackish estuaries and ascending freshwater river mouths before transitioning to offshore marine environments as adults.

Diet

Horse-eye jacks are active, fast-swimming carnivores that feed primarily on smaller fish, shrimp, and various aquatic invertebrates. Equipped with strong outer canine teeth and an inner tooth band in the upper jaw, alongside a single row of teeth in the lower jaw, they are well-adapted for capturing quick, agile prey. Their large eyes with developed adipose eyelids allow them to hunt effectively in lower light levels or turbid water. Hunting often occurs in groups near reef walls, open water, or artificial structures. Horse-eye jacks utilize their high speed and coordinated schooling tactics to corner and overwhelm baitfish. Research has documented specific hunting strategies where horse-eye jacks use man-made structures such as dock pilings to corner and attack schools of silversides, disrupting the prey's stereotyped escape movements to increase capture success. While adults forage across offshore reefs and open pelagic zones, juveniles hunt along shallow sandy or muddy coastal bottoms, preying on small crustaceans and larval fishes. Feeding occurs throughout the day, often intensifying during periods of strong tidal currents around reef points.

Did You Know?

Fun Facts

Named for their exceptionally large eyes, horse-eye jacks possess protective adipose eyelids that assist vision in deeper or murky waters.

They sometimes form unusual interspecies pairings, swimming side-by-side with puddingwife wrasses across the reef.

Juvenile horse-eye jacks feature five dark vertical bands along their flanks that disappear as they grow into adults.

The species is known to develop hyperostosis, a condition causing swollen or thickened bone structures in its skeleton.

Start Your Adventure

Ready to Dive with This Animal?

Explore our liveaboard expeditions to the best diving destinations