Horse-eye Jack

Fascinating facts about the Horse-eye Jack

• In 1831 Swiss naturalist Louis Agassiz first described the horse-eye jack from a Brazilian specimen, publishing the name Caranx latus alongside three other jacks. That early work also introduced the synonym Caranx lepturus, which later fell back to C. latus because it appeared first in the same volume. The story shows how a single 19th-century paper still decides the official name of this Atlantic predator today.
• The biggest horse-eye jack on record measured 101 cm long and tipped the scales at 13.4 kg, though most individuals are under 60 cm. Its dorsal fin carries eight spines up front, then one spine plus 19–22 soft rays, while the anal fin has two detached spines followed by one spine and 16–18 soft rays. Those precise counts help anglers and scientists tell it apart from its crevalle cousin.
• Large, protruding eyes sit beneath a thick adipose eyelid, giving the fish its common name. The pectoral fin is falcate and actually longer than the head, and the lateral line bears 32–39 strong scutes on its straight section. Such features let the jack spot prey in the shimmering, open water of the subtropical Atlantic.
• From Bermuda down to Rio de Janeiro in the western Atlantic, and from St. Paul's Rocks to Ascension Island in the east, the horse-eye jack roams pelagic zones up to 140 m deep. Juveniles linger near shore on sandy or muddy bottoms, while adults often school with crevalle jack or even pair with the wrasse Halichoeres radiatus. Their wide range and mixed-species gatherings reveal a flexible social life rarely seen in other jacks.
• The International Game Fish Association records a 32-lb (14.51 kg) world-record catch taken by Terry Lee Ramsey off Texas, confirming the species as a prized game fish. Yet the same fish can carry the ciguatera toxins C-CTX-1 and C-CTX-2, whose lethal doses are just 3.6 µg /kg and 1 µg /kg respectively. This contrast reminds anglers that a trophy catch may also hide a hidden health risk.

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