Yellowtail sergeant (Abudefduf notatus)
Source-cited species reference: taxonomy from WoRMS, biology from FishBase, occurrence map from GBIF, conservation from IUCN Red List, description from Wikipedia.
The yellowtail sergeant (Abudefduf notatus) is a species of damselfish in the family Pomacentridae native to the Indo-Pacific. It can grow to a maximum total length of 17 cm.
- Scientific name
- Abudefduf notatus
- Authority
- (Day, 1870)
- Family
- Pomacentridae
- Order
- Ovalentaria incertae sedis
- Maximum length
- 17 cm
- Depth range
- 1–12 m
- Habitat zone
- reef-associated
- Iucn red list
- Least Concern
- Gbif occurrence records
- 411
Classification (WoRMS)
Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Ovalentaria incertae sedis · Family: Pomacentridae · Genus: Abudefduf.
Accepted name: Abudefduf notatus · Authority: (Day, 1870) · Taxonomic status: accepted · AphiaID: 212870.
Synonyms and superseded combinations recorded for this taxon: Abudefduf clarki Snyder, 1911; Chrysiptera paucifasciata Fowler, 1946; Glyphidodon notatus Day, 1870; Indoglyphidodon abbotti Fowler, 1944.
Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=212870 (CC BY 4.0). Accessed 2026-09-23.
Biology and life history (FishBase)
Measured values published by FishBase for Abudefduf notatus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.
Maximum length: 17 cm · Depth range: 1–12 m · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 10 of 100 · Fishery importance: of no interest.
FishBase notes: Found in small groups along upper edges of sheltered drop-offs. Also found in rocky inshore reefs with moderate to strong wave action. In roving aggregations and somewhat difficult to approach (Ref. 9710). Oviparous, distinct pairing during breeding (Ref. 205). Eggs are demersal and adhere to the substrate (Ref. 205). Males guard and aerate the eggs (Ref. 205).
Source: FishBase species summary (SpecCode 5686) — https://www.fishbase.se/summary/Abudefduf-notatus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.
Distribution and occurrence records (GBIF)
411 georeferenced occurrence records for Abudefduf notatus are published through GBIF from 30 countries or marine areas. The map above plots 126 distinct locations from a sample of 411 records, omitting 15 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.
Most records by country or area: South Africa (84); Japan (51); Thailand (46); Korea, Republic of (38); Indonesia (33); Seychelles (27); Christmas Island (22); Chinese Taipei (16); Yemen (12); French Southern Territories (10); Maldives (9); Mozambique (8); United States Minor Outlying Islands (8); India (6); Réunion (6).
Marine regions with a valid WoRMS distribution record: Mozambican Exclusive Economic Zone; Seychellois Exclusive Economic Zone; South Africa (country).
Source: GBIF Occurrence Search (taxonKey 2398703) — https://www.gbif.org/occurrence/search?taxon_key=2398703&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=212870 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.
Conservation status (IUCN Red List)
The IUCN Red List assesses Abudefduf notatus (Day, 1870) as Least Concern (code LC). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.
Source: IUCN Red List of Threatened Species (taxon 188537) — https://www.iucnredlist.org/species/188537/0; GBIF IUCN Red List category endpoint (taxonKey 2398703) — https://api.gbif.org/v1/species/2398703/iucnRedListCategory. Accessed 2026-09-23.
Description and natural history (Wikipedia)
This species of damselfish is found in the Indo-Pacific. In the Indian Ocean, it occurs in the Gulf of Aden, the Arabian Sea, eastern Africa, Madagascar, Seychelles, the Maldives, Sri Lanka, the Andaman Sea, Indonesia, and Australia. In the Pacific Ocean, it occurs in the Gulf of Thailand, Indonesia, the Great Barrier Reef around Australia, the Philippines, Taiwan, Japan, New Caledonia, and various islands in the western Pacific Ocean. It typically occurs at depths of 1 to 12 m. Adults live in coral reefs and lagoons while juveniles are found in the open sea.
The species can grow up to a maximum length of up to 17 cm. It is gray with 5 vertical black bands and a yellow caudal fin. It has 13 dorsal spines, 13 to 14 dorsal soft rays, 2 anal spines, and 13 to 14 anal soft rays.
Abudefduf notatus forms roving aggregations which are noted to be rather difficult to approach. It is an oviparous species, with individuals forming distinct pairs during breeding and males guarding and aerating eggs.
Abudefduf notatus is found in the aquarium trade.
Source: Wikipedia: Abudefduf notatus — https://en.wikipedia.org/wiki/Abudefduf_notatus (CC BY-SA 4.0). Accessed 2026-09-23.
Frequently Asked Questions
Who is Yellowtail sergeant (Abudefduf notatus)?
The yellowtail sergeant is a species of damselfish in the family Pomacentridae, originally described by Day in 1870. It is a native Indo-Pacific reef fish most easily identified by the yellow coloration on its tail region.
What are Yellowtail sergeant (Abudefduf notatus)'s powers/role?
As a typical damselfish, it helps regulate microalgae and small invertebrate populations on coral reefs, contributing to overall reef balance. It is a mid-sized reef dweller, reaching a maximum total length of 17 cm.
Where does Yellowtail sergeant (Abudefduf notatus) live?
This species is distributed across the Indo-Pacific region and is generally found in shallow waters ranging from 1 to 12 meters depth. It favors reef-associated habitats where it can forage and shelter among corals and rocky structures.
Why is Yellowtail sergeant (Abudefduf notatus) important?
Its grazing activity helps prevent algal overgrowth that could otherwise smother living coral, making it a useful contributor to reef ecosystem health. Its presence is often cited as a sign of a functioning coral reef community in Indo-Pacific waters.
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