Almaco Jack

Encountering almaco jacks underwater is a thrilling experience for scuba divers exploring offshore sites and deep wrecks. Because these pelagic fish are wide-ranging and inquisitive, they often approach divers out of pure curiosity. One of the most unique and documented behaviours of the almaco jack involves skin parasite removal. In the open ocean, these fish commonly scrape parasite-laden skin against the rough, denticle-covered skin of passing sharks. On dive sites where sharks are absent, almaco jacks have been observed mistaking scuba divers for sharks, approaching closely to rub their sides against neoprene suits, dive gear, or fins.

When interacting with almaco jacks, divers should maintain calm, predictable movements and avoid sudden, erratic gestures that might startle the school. Streamline your equipment to prevent dangling gauges or hoses from snagging if a fish brushes past you. Avoid actively chasing or grabbing at the fish; instead, allow them to set the distance and control the interaction. Because almaco jacks are often encountered in deep water column environments around drop-offs and wrecks, divers must maintain strict buoyancy control and keep a close watch on their depth, bottom time, and gas supply.

Almaco jacks inhabit tropical and warm temperate waters around the globe, meaning encounters are possible year-round depending on the geographic region. Because they spawn continuously—as frequently as weekly throughout the year—their presence on offshore reefs and deep structures is not tied to a single brief breeding window, though local seasonal conditions influence dive accessibility and sighting frequency.

In the Western Atlantic, Gulf of Mexico, and Caribbean, almaco jacks can be observed throughout the year, with sightings around artificial reefs and deep wrecks often peaking during warmer summer and early autumn months when water temperatures are high and ocean swells are calm. Across the Pacific Islands, including Hawaii where they are heavily ranched in deep net pens, wild almaco jacks are present year-round around steep drop-offs. In the Eastern Pacific, from California down through Baja California, the Galápagos, and Peru, encounters are best during warmer water seasons when pelagic activity increases near coastal slopes. In the Northeast Atlantic and Mediterranean, sightings are more sparse and seasonal, primarily occurring during the warmer summer months from July to October.

The almaco jack is a pelagic species primarily associated with open-ocean environments, deep waters beyond the continental shelf, and offshore structure. While they are capable of traversing vast ocean distances, they frequently concentrate along continental slopes, deep outer reef drop-offs, underwater pinnacles, and artificial structures. Notably, almaco jacks visit shipwrecks much more frequently than most other carangid species, using them as focal points for shelter and foraging.

Their depth range spans from shallow waters near 5 metres down to 160 metres deep, though they are most commonly observed swimming in the upper water column between 5 and 35 metres. Geographically, almaco jacks enjoy an expansive global distribution. In the Atlantic, they range from Cape Cod to northern Argentina (though rare off the Carolinas) and extend east to the Azores, Madeira, Portugal, the Bay of Biscay, and parts of the Mediterranean. In the Indo-West Pacific, they are found from Kenya and South Africa to Japan, the Mariana Islands, New Caledonia, and Hawaii. In the Eastern Pacific, their range extends from California south to Peru and the Galápagos Islands.

Almaco jacks are opportunistic, carnivorous predators with a diet consisting primarily of smaller marine organisms. They actively hunt both day and night, using their speed, stamina, and vision to capture prey in open water or near submerged structures. Their primary food sources include various small baitfish species that congregate in pelagic zones or around reef systems.

In addition to small fish, almaco jacks feed extensively on invertebrates such as small squid, octopuses, crabs, and shrimp. They often hunt in small groups, swarming schools of baitfish or picking off benthic and free-swimming crustaceans along deep slopes and wrecks. Because wild almaco jacks feed on reef-associated prey, bioaccumulation of ciguatoxins produced by microscopic dinoflagellates can occur, occasionally causing ciguatera fish poisoning in humans who consume large wild individuals. Conversely, commercially farmed almaco jacks fed a controlled diet do not harbour these dinoflagellates and remain free of ciguatoxin.