What is the conservation status of Blackbar Soldierfish?

Blackbar Soldierfish: Not Evaluated

Blackbar Soldierfish

SizeUnknown

LifespanUp to 10 years

StatusNot Evaluated

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Only destinations where this animal occurs.

The Blackbar Soldierfish at a glance

The blackbar soldierfish (Myripristis jacobus) is a striking reef-associated fish easily recognized by its vibrant colouration and prominent markings. Its body is bright red to dark orange along the dorsal surface, gradually paling to a silvery sheen on the belly. A bold, dark brown to black vertical bar runs behind the head, extending down the edge of the gill cover to the base of the pectoral fin. Another dark bar passes through its unusually large, dark eyes, while all fins except the transparent pectorals feature distinct white tips and borders.

Morphologically, this species possesses a deep, robust, and laterally compressed ovate body, capped by a blunt snout and a convex forehead. The soft dorsal and anal fins are covered with fine scales, terminating in pointed lobes that complement a strongly forked caudal tail. Unlike many related squirrelfishes, the blackbar soldierfish lacks a prominent preopercular spine, though the edges of its head bones and operculum are distinctly serrated. Its body is covered in large, rough scales that provide a coarse texture.

Behaviour & reproduction

Size: Unknown
Weight: Up to 360 g
Lifespan: Up to 10 years
Status: Not Evaluated

The Blackbar Soldierfish, Myripristis jacobus, is a nocturnally active species typically found sheltering in caves, under ledges, or within coral crevices during daylight hours, often forming small aggregations or larger schools. At night, these fish emerge to forage for zooplankton, their large eyes adapted for low-light conditions. Regarding reproduction, this species is oviparous, releasing eggs externally. While precise details on spawning seasons for Myripristis jacobus are not consistently documented across its range, many soldierfish species engage in broadcast spawning, where eggs and sperm are released into the water column, often occurring at specific times such as dusk or dawn around the full moon. Fertilised eggs are pelagic, drifting as plankton before hatching into larvae. The incubation period and the exact number of eggs released per spawning event are not specifically detailed for this species in general literature, but development involves a planktonic larval stage before juveniles settle in suitable reef habitats. Sexual maturity is attained once individuals reach a certain size, typically around 10-12 cm in total length.

Diving Tips

When diving in search of the blackbar soldierfish, focus your attention on sheltered structural features of the reef. During day dives, scan beneath table corals, deep rock ledges, swim-throughs, and cavern entrances. They are typically encountered in depth ranges between 2 and 35 metres, though they can inhabit waters from the surface down to 210 metres. Look closely at the ceiling of overhangs, as these fish often hover completely upside-down.

Because blackbar soldierfish possess large eyes adapted for low-light environments, they are particularly sensitive to intense light sources. When using a dive torch or camera strobe, avoid pointing bright beams directly at them for prolonged periods. Diffused lighting or angling your light slightly away allows you to appreciate their vivid red colouration and black shoulder bar without causing distress.

Approach resting aggregations with slow, smooth movements. Maintain neutral buoyancy to avoid disturbing fine sediment on cave floors. If you give them space and refrain from blocking their exit routes into deeper crevices, these curious fish will often hover comfortably in place, providing excellent opportunities for underwater photography.

Fun facts about the Blackbar Soldierfish

The species name 'jacobus' derives from 'Frère-Jacques' (Brother Jim), its local common name in Martinique.
Blackbar soldierfish are known to swim completely upside-down along the ceilings of underwater caves and coral ledges.
They possess exceptionally large eyes adapted specifically for navigating and hunting plankton in near-total darkness.
Although occasionally sold fresh in commercial markets, they are not a popular food fish, but are occasionally kept in aquariums.

Best time to see the Blackbar Soldierfish

The blackbar soldierfish is a non-migratory resident species found across tropical and subtropical waters of the Atlantic Ocean, maintaining stable populations year-round. Because these fish reside within resilient coral and rocky reef habitats from 37°N to 23°S, their presence on dive sites does not fluctuate seasonally, making encounters possible during any month of the year.

In tropical regions such as the Caribbean Sea, the Bahamas, and the West Indies, diving conditions remain warm and favourable year-round, offering consistent visibility to observe blackbar soldierfish resting in reef overhangs. In northern subtropical areas like North Carolina, the summer and early autumn months bring warmer water temperatures and calmer sea conditions, providing the best opportunities to explore deeper offshore reefs where these fish shelter.

Similarly, in Eastern Atlantic territories including Cape Verde, Ascension, Príncipe, and St. Helena, year-round water temperatures support steady populations. Local seasonal dive planning should focus on optimal sea conditions and underwater visibility for specific geographic regions rather than the biological movements of the fish, as their depth preference and nocturnal lifestyle remain consistent throughout the year.

Where the Blackbar Soldierfish lives

The blackbar soldierfish is a strictly marine, reef-associated species found across a broad depth gradient ranging from shallow waters at 1 metre down to deep offshore zones of 210 metres. However, it is most commonly encountered in depths between 2 and 35 metres along inshore and offshore reef systems. It prefers complex structural habitats provided by hard corals, rocky ledges, sea anemone margins, and deep underwater caves.

Geographically, *Myripristis jacobus* exhibits a wide transatlantic distribution. In the Western Atlantic, its native range extends from North Carolina in the United States, through the Bahamas and the northern Gulf of Mexico, across the entirety of the West Indies and Caribbean Sea, and southward down the coast of Brazil.

In the Eastern Atlantic, the species occurs around isolated oceanic archipelagos and islands, including St. Paul's Rocks, Cape Verde, Príncipe, Ascension Island, and St. Helena. Within these varied localities, it remains firmly tied to the benthic layer, sheltering close to the bottom substrate during the day and utilizing the structural complexity of reefs for protection from open-water currents and predators.

What the Blackbar Soldierfish eats

The blackbar soldierfish is primarily a nocturnal carnivore and planktivore, emerging from reef crevices at dusk to hunt in the water column and near the substrate. Its diet consists predominantly of planktonic organisms and zooplankton suspended in the water column, which it captures using its large, light-sensitive eyes to locate movement in dim light.

In addition to smaller zooplankton, *Myripristis jacobus* actively preys upon pelagic fish larvae and floating fish eggs. It also consumes mobile benthic crustaceans, including various species of small shrimps and crabs that venture out onto the reef surface during the night.

During the day, feeding activity ceases as the fish form quiet aggregations inside caves and under overhangs to conserve energy. As night approaches, these groups disperse into nearby open waters. Their relatively large, oblique mouth enables them to efficiently swallow mobile planktonic prey and small invertebrates whole, playing an important ecological role in transferring energy from pelagic plankton into the localized reef food web.