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Yellowband Fusilier

One of the most abundant schooling fish on Koh Tao’s offshore pinnacles, the Yellowband Fusilier travels in dense, fast-moving schools that sweep across the water column in flashes of yellow and blue-green. Where fusiliers gather, predators follow — making them as much a signal as a spectacle.

Least Concern
Yellowband Fusilier: One of the most abundant schooling fish on Koh Tao's offshore pinnacles, the Yellowband Fusilier travels in dense, fast-moving schools that sweep across the water column in flashes of yellow and blue-green. Where fusiliers gather, predators follow — making them as much a signal as a spectacle.
Scientific Name
Pterocaesio chrysozona
Typical size
Up to 21cm
difficulty to see
Common
Best Time to See
Year Round

Overview

The Yellowband Fusilier is one of the most visually striking schooling fish on Koh Tao’s reefs — a slender, fast-moving species identifiable by the vivid yellow stripe running the length of its body against an iridescent blue-green back. They travel in dense, fast-moving schools that sweep across pinnacles and open water, feeding on zooplankton in the water column before retreating to the reef when threatened. Where you find fusiliers in numbers, predators are rarely far behind.

Conservation Status
Least Concern
Danger Level
Harmless
Typical Depth 
5-35m
Behavior
Schooling

Snorkel with Yellowband Fusiliers

We regularly encounter this species on our dives and guided snorkel trips around Koh Tao.
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Identification

Rarely seen alone. Yellowband Fusiliers travel in schools ranging from dozens to several hundred individuals, often forming tight, swirling columns when a predator is near. The collective flash of yellow stripes catching the light at depth is one of the most immediately recognisable sights on a Koh Tao pinnacle dive.
Logan Brown

Conservation Notes

Yellowband Fusiliers are not a species of conservation concern, but the health of their schools is a reliable indicator of reef ecosystem balance. Healthy fusilier populations signal good plankton productivity and an intact predator-prey chain. Avoid disturbing schooling behaviour — chasing or swimming through a school stresses the fish and disrupts feeding activity.

Yellowband Fusilier Facts

Fusiliers are one of the primary reasons large predators like trevally and barracuda patrol Koh Tao's pinnacles — the schools act as a reliable food source that draws the big fish in.
They are closely related to snappers (family Lutjanidae) but have evolved a more streamlined, torpedo-shaped body suited to open-water schooling rather than reef-hugging.
Yellowband Fusiliers are protogynous hermaphrodites — some females can transition to male as they mature, a reproductive strategy common across several reef fish families.

Where to find them

Yellowband Fusiliers are a near-constant presence at Koh Tao’s offshore pinnacles. Southwest Pinnacle and Chumphon Pinnacle typically host the largest aggregations — look for dense, fast-moving columns sweeping up from depth or hanging mid-water just off the structure. At Sail Rock, schools often circle the pinnacle in open water, particularly on dives with a light current running. They tend to be most active and visible in the mid-water column between 10–20m.

Southwest Pinnacle

Pinnacle • 5–30 m

Chumphon Pinnacle

Pinnacle • 14–35 m

Tanote Bay

Reef • 2–20 m

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