Fish Active at night

Bigeye Trevally

Caranx sexfasciatus

iNaturalist Wikipedia

A shimmering sentinel of the tropical reef, the Bigeye Trevally is famous for forming breathtaking 'fish tornados' by day and hunting with precision by night. With its striking silver body and iconic white-tipped fin, it is a master of the Indo-Pacific depths.

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Quick Identification

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Size

Typically 60-120 cm (24-47 in) in length; can weigh up to 18 kg (40 lbs)

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Colors

Silvery-blue to dusky grey on top, fading to silver-white below; fins are generally dusky, but the second dorsal fin has a distinct white tip

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Key Features

Distinctive white tip on the lobe of the second dorsal fin
Small black spot on the upper edge of the operculum (gill cover)
Large eyes with a well-developed adipose eyelid
Deep, compressed silver body

When You’ll See Them

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Activity pattern Active at night

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Peak hours 7 PM - 5 AM

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Season Year-round

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Diet A carnivorous predator that feeds primarily on small reef fish, but also supplements its diet with crustaceans like shrimp and various cephalopods such as squid.

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Habitat Tropical marine environments including coral reefs, seaward slopes, deep lagoons, and occasionally brackish estuaries.

public Geographic range

Where Does the Bigeye Trevally Live?

The Bigeye Trevally is a wide-ranging marine species found throughout the tropical and subtropical waters of the Indian and Pacific Oceans. Its range extends from the eastern coast of South Africa and the Red Sea, across to northern Australia and Japan, and reaches as far east as the Pacific coast of the Americas, from California down to Ecuador and the Galapagos Islands. This species is a resident of coastal shelf areas and is rarely found in the open ocean far from reef structures.

Basemap © OpenStreetMap contributors

9 Countries

140M km² Range

Least Concern Conservation

AU Australia ID Indonesia PH Philippines JP Japan ZA South Africa TH Thailand MX Mexico US United States Papua New Guinea

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iNaturalist / Verified observation data

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Behavior

Bigeye Trevally are famous for their highly social behavior during daylight hours. They often form massive, slow-moving schools that create towering cylindrical columns, often referred to as 'fish tornados.' These schools typically hover near reef drop-offs, slopes, or large coral structures, using the formation as a defense mechanism against larger predators while they rest.

As the sun sets, the schools disperse as the fish transition into an active hunting phase. Unlike many other jack species, the Bigeye Trevally is primarily nocturnal, using its enlarged eyes to navigate and hunt in low-light conditions. While they are powerful predators, they are generally non-aggressive toward divers and are a prized sight for underwater photographers due to their shimmering scales and predictable schooling locations.

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Camera Tips

Capturing the Bigeye Trevally requires specialized underwater camera equipment, as they are strictly marine inhabitants. For the best results, position a stationary underwater camera (like a reef-cam or a GoPro on a weighted tripod) near a prominent reef corner or a 'cleaning station' where current flows are consistent. These fish gravitate toward moving water, which brings in oxygen and food. Angle your camera slightly upward toward the surface; this allows the natural light to reflect off their silver bodies, creating a high-contrast, shimmering effect against the blue water.

Because they are most active at night, underwater lights are essential for capturing hunting behavior. Use wide-angle video lights with a high CRI (Color Rendering Index) to bring out the natural silver and blue hues of the fish. If you are filming during the day to capture their famous 'tornados,' use a wide-angle lens. A standard lens will often fail to capture the sheer scale of the school, whereas a wide-angle or fisheye lens can fit the entire cylindrical formation into the frame.

If you are using an AI-powered camera system, ensure it is set to a high frame rate (at least 60fps). Trevally are fast-moving predators, and higher frame rates will help the AI accurately track their movement and prevent motion blur. For baited remote underwater video (BRUV) setups, small amounts of chopped oily fish can bring them closer to the lens, but be aware that this may also attract larger sharks or eels which could damage a loosely secured camera rig.

Similar Species

Species that look similar or are commonly confused with Bigeye Trevally.

Giant Trevally

Much larger and more aggressive with a steeper head profile and lacks the white tip on the dorsal fin.

Bluefin Trevally

Easily distinguished by electric blue fins and small dark spots covering its upper body.

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Frequently Asked Questions

Bigeye Trevally are primarily nocturnal hunters. While they are easily seen in large schools during the day, they are actually resting and conserving energy during this time. Their peak hunting activity occurs between dusk and dawn, aided by their large eyes which are specially adapted for low-light vision.

To attract Bigeye Trevally, place cameras near reef drop-offs where currents are strong. You can use a 'BRUV' (Baited Remote Underwater Video) setup with oily fish like sardines as bait. However, simply finding a known schooling site during the day is often enough to capture hundreds of them without bait.

They are aggressive carnivores that mainly eat small fish found around the reef. They also consume crustaceans (like crabs and shrimp) and cephalopods (like squid) when available.

They are not found in inland suburban areas, but they are very common near coastal suburban regions with access to tropical reefs. They are frequently spotted by divers near coastal piers, jetties, and artificial reefs in places like Florida, Hawaii, and Queensland.

The easiest way to tell them apart is by looking at the fins and eyes. Bigeye Trevally have a distinct white tip on their second dorsal fin and much larger eyes relative to their head size. Giant Trevally (GTs) are much bulkier, have a more steep, blunt head profile, and lack the white fin tip.

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