Blackspot Sergeant
ExploreFish
Blackspot Sergeant
abudefduf sordidus
The Blackspot Sergeant (Abudefduf sordidus) is a resilient and territorial damselfish commonly encountered in the shallow surge zones and tide pools of the Indo-Pacific. Known for their spirited nature, these fish are an entertaining sight for snorkelers and beachgoers, often darting aggressively to defend their small patches of turf. While many reef fish retreat to deeper, calmer waters, the Blackspot Sergeant thrives in highly oxygenated, wave-swept environments where they graze on algae and small invertebrates. Their adaptability allows them to flourish even in marginally degraded or highly dynamic habitats, making them a familiar and lively staple of rocky shorelines. Observing their fast-paced, industrious behavior provides a wonderful window into the complex social dynamics of shallow-water reef ecosystems.
Habitat: Found in the shallow waters of the Indo-Pacific, typically inhabiting wave-swept rocky shores, coral reef flats, and tidal pools.
Appearance
This sturdy damselfish features a light gray to silvery body adorned with five to six dark, vertical bands that fade slightly towards the belly. Its most defining characteristic, giving it its common name, is a prominent black saddle-like spot located on the upper edge of the caudal peduncle, just before the tail fin. Juveniles often display brighter overall coloration with a distinct black spot at the base of the dorsal fin. They possess a moderately deep, compressed body shape typical of the Abudefduf genus, allowing them to maneuver easily in turbulent waters, and can grow up to 24 centimeters in length.
KingdomAnimaliaPhylumChordataClassActinopterygiiOrderBlenniiformesFamilyPomacentridaeGenusAbudefduf
Category
FishRarity
Common
Danger
1/5 · Very low
Snaps
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Interesting facts
During extreme low tides, juveniles are frequently trapped in tide pools, relying on their incredible hardiness to survive rising temperatures until the tide returns.
The genus name 'Abudefduf' is derived from Arabic, translating roughly to 'father of the prominent sides,' a nod to their deep-bodied, compressed shape.
Unlike many reef fishes that migrate to deeper, safer waters as they mature, this species spends almost its entire life in very shallow, highly turbulent waters.
When preparing a nesting site, the male Blackspot Sergeant vigorously cleans a patch of rock or dead coral and then performs a rapid mating dance to attract females.
Special abilities
Ability
Surge Zone Navigation
Perfectly adapted to withstand powerful wave action, allowing them to forage safely in highly turbulent, oxygen-rich shallow waters where competitors cannot.
Ability
Aggressive Nest Guarding
Males fiercely protect their benthic egg clutches from predators and territorial intruders, often charging at creatures much larger than themselves.
Ability
Tide Pool Tolerance
Juveniles exhibit a remarkable biological tolerance for rapid fluctuations in salinity and temperature, enabling them to survive low tides in isolated rock pools.
Measurements & details
- Length
- 10-24 cm
- Weight
- 0.05-0.3 kg
- Lifespan
- 3-6 years
- Top Speed
- 15 km/h
- Clutch Size
- 1000-20000
- Incubation
- 3-7 days
Diet & Feeding
They are opportunistic feeders that primarily graze on benthic algae while also actively consuming a variety of small invertebrates.
Age differences: Juveniles rely heavily on small crustaceans found in tide pools, while mature adults graze more extensively on filamentous algae.
Primary Foods
- Benthic algae
- Copepods
- Amphipods
- Polychaete worms
- Zooplankton
Foraging Method
- Foraging
Ecological connections
eaten by
Giant Moray
Gymnothorax javanicus
Larger reef predators like the Giant Moray ambush resting Blackspot Sergeants in the reef crevices at night.
competitor
Indo-Pacific Sergeant
Abudefduf vaigiensis
Competes directly for territory and algal resources on shallow reef flats.
hunts
Harpacticoid Copepod
Harpacticoida
Blackspot Sergeants actively hunt these tiny crustaceans in the water column and along the benthos.
Traits
No trait badges are assigned for this object yet.
Also known as
No aliases listed yet.
Collections
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Safety
Danger
1/5 · Very low
No special safety notes yet.
Frequently Asked Questions
How to identify Blackspot Sergeant?
The easiest way to identify Blackspot Sergeant is to use the Snappit nature identifier app.
How long is Blackspot Sergeant?
10-24 cm
How much does Blackspot Sergeant weigh?
0.05-0.3 kg
How long does Blackspot Sergeant live?
3-6 years
How fast can Blackspot Sergeant move?
15 km/h
What does Blackspot Sergeant eat?
They are opportunistic feeders that primarily graze on benthic algae while also actively consuming a variety of small invertebrates.
Where is Blackspot Sergeant usually found?
Found in the shallow waters of the Indo-Pacific, typically inhabiting wave-swept rocky shores, coral reef flats, and tidal pools.
How does Blackspot Sergeant hunt?
Foraging
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