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Fun Facts about Fusilier Fishes

[Phylum: Chordata] [Class: Actinopterygii (ray-finned fish)] [Order: Perciformes] [Family: Caesionidae]

Despite the "military" reference, fusilier fish are not an army even though they do resemble a squadron when they school together in huge numbers.

In fact, fusilier fishes are streamlined Perciformes (perch-like) related to snappers. But unlike the snapper, fusiliers do not feed on larger prey.

Habitat and Geographical Range of Fusiliers

You will find fusilier fish (family Caesionidae) in the warm tropical and subtropical waters of the Indo-Pacific region and the Coral Triangle.

They often form large schools near shallow coral reefs, especially in:

The Indian Ocean (the Maldives, east coast of Africa)
The Red Sea (extending from Suez in Egypt)
The Pacific Ocean (the Philippines, Indonesia, the Great Barrier Reef)

The fusilier fish species is important for the health of reef ecosystems because they help to keep plankton populations in check.

Fusiliers thrive best swimming around coral formations and drop-offs, usually near the surface. Even so, they also venture deeper to depths approaching sixty (60) metres (200 feet).

Fusiliers Fish Characteristics

There are more than twenty (20) validated species of Caesionidae around the world. In fact, most of the Malaysia dive sites provide ideal habitats for all four genera and almost all of the scientific classifications.

The easy way to recognise fusiliers is by their cylindrical body shape, protrusible small mouth with small teeth, and deeply forked caudal fin.

Fusilier Fish Size

The slender fusilier (Gymnocaesio gymnoptera) is one of the smallest fusiliers measuring up to eighteen (18) cm long (7 inches).

Yet, the yellowtail fusilier (Caesio cuning) is one of the biggest and full grown adults can reach a total maximum length of sixty (60) centimetres (24 inches).

Fun Fact: As well as being very fast and agile swimmers, fusiliers are also masters at changing colour. Depending on why they need to do so, they often switch body colouration between bright blue hues, silver greys, and brilliant yellows.

What Do Fusilier Fish Eat?

By and large, fusiliers feed solely on planktonic material and zooplankton (tiny invertebrate animals) while they swim in the midwater column.

Fusilier Fishes These schooling reef fish also feed by picking on suspended phytoplankton (microscopic algae) as it drifts with the water currents.

Some species may also add tiny aquatic crustaceans, fish eggs, and other drifting organic matter to their daily diet.

Despite being very active during daytime, they are diurnal planktivores that tend to seek shelter and some safety within the reef structures as the daylight disappears.

How Do Fusiliers Reproduce?

Like most reef-associated fishes, fusilier fish (family Caesionidae) also reproduce through a process known as "broadcast spawning" - usually taking place at dusk or dawn.

In other words:

They spawn in large congregations and release eggs and sperm into the open water. Doing so often increases the likelihood of fertilisation and it also reduces some predation on the eggs.

Following a successful external fertilisation, the eggs continue drifting with the ocean currents. Like many marine vertebrates, fusiliers do not exhibit parental care. Instead, their population growth relies on the high number of eggs produced by the females.

The fertilised eggs will hatch into planktonic larvae during the pelagic larvae phase of the process. They feed on microscopic plankton and they can be floating in open water for several weeks.

After the larvae grow and start developing into juveniles, they will find a suitable coral reef to settle. Here, they will mature into adults and join the schooling behavior that is typical and widespread in all fusilier fishes.

Fusilier Fish Species List

Banana Fusilier (Pterocaesio pisang)

Blue and Gold Fusilier (Caesio caerulaurea)

Capricorn Fusilier (Pterocaesio capricornis)

Cenderawasih Fusilier (Pterocaesio monikae)

Dark-banded Fusilier (Pterocaesio tile)

Double-lined Fusilier (Pterocaesio digramma)

Goldband Fusilier (Pterocaesio chrysozona)

Many people know goldband fusiliers as the black-tipped fusilier (Pterocaesio chrysozona). They are widespread in the Red Sea and Indo-Pacific regions. They exhibit non-migratory behavior and are mainly found in schools around coral reefs and deep lagoons.

They are commonly found at depths from 5 - 30 meters during the day time but they return to the reef at night for shelter.

They display a yellow stripe on both sides, a white-pink belly, and their dorsal area is blue-brown. They filter feed on zooplankton and they are oviparous fast breeders.

Goldsash Fusilier (Caesio xanthalytos)

Lunar Fusilier (Caesio lunaris)

Marr's Fusilier (Pterocaesio marri)

Mottled Fusilier (Dipterygonotus balteatus)

One-stripe Fusilier (Pterocaesio trilineata)

Randall's Fusilier (Pterocaesio randalli)

Redbelly Yellowtail Fusilier (Caesio cuning)

The yellowtail is also known as the redbelly or robust fusilier. The species is widespread in most areas of the Asia Pacific, especially at the best Thailand dive sites.

Fusilier fishes are related to the snapper species. But many are less than 50 centimetres in length, so they are noticeably smaller and slender.

They school in large numbers around silt reefs predominantly at the crest of steep slopes feeding on zooplankton - often down to 30 metres deep.

Their colour permeates from their usual yellow and blue to red and green when they are inactive at night time.

They use their extensible upper jaws to feed on plankton blooms in the Indo-Pacific regions. They have been seen as big as 60 cm in length but adults typically grow to 40 cm.

Slender Fusilier (Gymnocaesio gymnoptera)

Striated Fusilier (Caesio striata)

Suez Fusilier (Caesio suevica)

Three-stripe Fusilier (Pterocaesio trilineata)

Variable-lined Fusilier (Caesio varilineata)

Wide-band Fusilier (Pterocaesio lativittata)

Yellow and Blueback Fusilier [Caesio teres]

Yellow and blueback fusiliers belong to the Lutjanidae family and are found in coral reef or lagoon habitats of Indo-Pacific and GBR regions. They assemble extensively in large schools at varying depths of five to fifty metres.

The fish has a white belly and dazzling petrol blue coloring above its underside. The upper back section from the beginning of its dorsal fin running through to its tail is intense yellow.

In contrast, most of their fins are white and they have a distinctive black patch around the joint of their pectoral fins. Fusiliers vary in size but adult yellow and bluebacks usually reach 40 cm in length.

They feed on zooplankton hovering above the reef in large schools. They are oviparous egg layers at breeding time. The female lays innumerable tiny pelagic eggs timing the spawning to coincide with the outgoing tides.

Yellowback Fusilier (Caesio xanthonota)

Yellowstripe Fusilier (Pterocaesio flavifasciata)

Threat and Predators

The reproductive strategy tends to ensure that a high proportion of the offspring will survive. Despite that, they face a high rate of predation and other environmental challenges beyond their control.

Plus, due to their moderate size and abundance, some fusilier species are preyed upon by various large marine animals, especially barracudas, dolphins, grouper fish, rays, reef sharks, and trevallies.

In addition, some diving seabirds may also target fusiliers fish species, especially the juveniles in shallow water, when they're within easy reach.

Humans also eat fusiliers for the mild, delicate flavour. Hence, they have become a popular target for fishermen and valued as a food source in many cultures.

Even though they are a tasty fish to eat, they are not generally overfished or overexploited through commercial fishing practices.

Pro Tip: The IUCN Red List of Threatened Species last assessed many of the fusilier phylum in 2019. They cited almost all of the species as being of "Least Concern" (LC) with stable populations.

Related Information and Help Guides

Note: The short video [1:01 seconds] presented by "Kidadi" contains extra fun facts and information about the fusilier fish species (Caesionidae).