Fish diurnal

Almaco Jack

Seriola rivoliana

The Almaco Jack is a sleek, deep-bodied powerhouse of the ocean, recognized by its impressive sickle-shaped fins and inquisitive personality. Often found patrolling offshore wrecks, this spirited predator is a thrill to witness on any underwater camera.

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Quick Identification

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Size

Typically 24-36 inches (60-90 cm) in length, though they can reach up to 52 inches (132 cm) and weigh over 100 lbs (45 kg).

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Colors

Dusky brown to olive-green upper body with silver-white undersides; features a dark diagonal stripe (nuchal bar) from the eye to the dorsal fin.

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Key Features

High, sickle-shaped (falcate) second dorsal and anal fins
Deep, laterally compressed body shape
Dark diagonal bar passing through the eye to the nape

When You’ll See Them

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Activity pattern diurnal

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Peak hours 6-10 AM, 3-7 PM

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Season Year-round

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Diet A carnivorous hunter that feeds on small baitfish, squid, octopus, and occasionally benthic crustaceans like crabs and shrimp.

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Habitat Primarily deep-water reefs and offshore structures, but occasionally found near coastal drop-offs and large docks.

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Behavior

Almaco Jacks are powerful, pelagic predators known for their inquisitive nature. Unlike many other reef fish that may flee at the sight of new objects, Almaco Jacks are famously curious and will often approach underwater cameras or divers to investigate. They are strong swimmers that utilize their deep-bodied shape to maneuver effectively around deep-water reefs, shipwrecks, and oil platforms.

While they are often found in small, loose shoals, larger individuals tend to be more solitary. They are opportunistic hunters, roaming the water column from the surface down to depths of over 500 feet. Their social behavior is generally peaceful toward similar-sized fish, but they are highly competitive when food is present, often using their speed to outmaneuver other predators during a feeding frenzy.

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Camera Tips

Capturing the Almaco Jack requires a specialized underwater setup, as these fish rarely venture into the shallow tide pools or shorelines where standard land cameras might reach. If you live near a deep-water dock or have access to a pier, mounting an underwater action camera (like a GoPro or a specialized submerged trail cam) at a depth of 5 to 15 feet is ideal. Focus your lens on structural elements like pilings or submerged debris, as these fish use such markers as navigation points and hunting grounds.

To draw them into the frame, utilize the Almaco Jack’s natural curiosity rather than just food. A 'flasher'—a piece of shiny, reflective metal or a CD hung on a line—will catch the sunlight and mimic the scales of a fleeing baitfish, often bringing a curious Jack right up to the camera lens. If local regulations allow, a mesh bait bag filled with oily fish like sardines or mackerel will create a scent trail that is nearly irresistible to these predators.

Because Almaco Jacks move with incredible speed when they strike, set your camera to a high frame rate (at least 60 frames per second) to avoid motion blur. If your camera allows for white balance adjustment, set it to 'Underwater' or 'Diving' mode to compensate for the loss of red light at depth, ensuring the olive and silver tones of the fish appear natural. Mid-morning is often the best time for filming, as the overhead sun provides maximum light penetration into the water column, making their silver flanks shimmer vividly against the blue background.

Similar Species

Species that look similar or are commonly confused with Almaco Jack.

Greater Amberjack

The Greater Amberjack has a more elongated body and a much shorter second dorsal fin compared to the Almaco's high, sickle-shaped fin.

Yellowtail Amberjack

Look for the bright yellow tail and the distinct yellow horizontal stripe along the midsection, which the Almaco Jack lacks.

Lesser Amberjack

The Lesser Amberjack is much smaller and has proportionally larger eyes relative to its head size.

Frequently Asked Questions

Almaco Jack are primarily diurnal, meaning they are most active during daylight hours. Their peak hunting times are usually around dawn and dusk when light levels change, allowing them to use their keen eyesight to ambush smaller prey fish.

The best way to attract Almaco Jack is by using reflective objects called flashers or by placing a scent-heavy bait bag near your camera. Their natural curiosity often drives them to investigate shiny objects or unusual vibrations in the water.

They are generalist carnivores. Their diet consists mostly of smaller fish like herring and sardines, but they also frequently consume squid, octopus, and occasionally crabs or shrimp found near the seafloor.

They are not found in suburban inland areas, but if you live in a coastal community with deep-water access, such as near a large harbor or pier, you may find them patrolling nearby structures.

The easiest way to distinguish them is by the fins. The Almaco Jack has a much taller, more curved (falcate) second dorsal fin compared to the shorter, more rounded fin of the Greater Amberjack.

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