Abudefduf saxatilis is a member of the pomacentridae family that
includes both the damselfishes and anemonefishes. This family is abundant in
the tropical and warm temperate waters of the world. The Seargeant major is a
small, laterally compressed rounded fish. There is a single nostril on either
side of the snout distinguishing it from the butterflyfishes and angelfishes.
It has a small, oblique terminal mouth. The upper part of the body is
yellowish with 5 vertical black bars. Sometimes a faint sixth bar can be
present. There is a black spot at the upper base of the pectoral fin (Randall
A. saxatilis is often observed on shallow reefs in large feeding
aggregations of up to a few hundred individuals (Randall 1996). This fish uses
different color phases for camouflage. The light phase is visible from below
when the sergeant major is swimming over the reef, while the dark phase allows
the fish to hide in the reef in response to danger. When males guard the red
or purple patches of eggs in their nests they become dark bluish (Randall
Potentially Misidentified Species
Abudefduf sexfasciatus Lacepede 1801
Abudefduf septemfasciatus Cuvier
Abudefduf vaigiensis Quoy and Gaimard 1825
HABITAT AND DISTRIBUTION
Abudefduf saxatilis is abundant in reef and rocky environments in the
Atlantic ocean (Molina et al. 2006). Populations have been recorded in the
western Atlantic ocean from as far north as Canada to Uruguay in South America
at depths ranging from 0 to 20 m. A. saxatilis is abundant on Caribbean
reefs (Randall 1996) and on the tropical coast of western Africa to Angola
where they form large feeding aggregations of up to a few hundred individuals. Juveniles are found in tide pools or in protected areas schooling close to
caves and shipwrecks. Adults are most common on shallow reefs.
Juveniles of Abudefduf saxatilis were recorded as one of the ten most
abundant species of fish occurring in the surveys in the Indian River Lagoon
(Lindemen and Snyder 1999).
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Abudefduf saxatilis grows to a maximum length of approximately 23 cm and
can weigh up to 0.2 kg. Males and females reach maturity at 10 cm and 8 cm,
Abudefduf saxatilis is abundant on tropical reefs and has been observed
to rapidly increase its population size in areas of recreational disturbance
where artificial food sources are created by fish feeding and habitat
disturbances (Medieros et al. 2007).
Sergeant majors are oviparous. Males prepare nests for egg masses on rocks,
reef outcrops, shipwrecks, and pilings. Spawning times vary depending upon
region. For example, Caribbean populations do not appear to exhibit a lunar
spawning pattern. Females in this region have been observed to spawn at
various times throughout the month (Foster 2004). During courtship males
actively chase females in the early hours of the day and spawning takes place
in the morning hours. Approximately 200,000 salmon or red colored, oval shaped
eggs measuring 0.5 to 0.9 mm in diameter are released in discrete, densely
packed monolayers that adhere to the substratum (Robertson et al. 1993). Once
fertilized the eggs turn greenish (with 96 hours). The male guards the eggs
until they hatch usually within 4-5 days after fertilization in the hour
following sunset (Robertson et al. 1993, Foster 2004).
Abudefduf saxatilis larvae have a reduced pelagic stage lasting 18-27
days and a post larval pelagic stage lasting 55 days (Molina et al. 2006). The
egg and larval development of laboratory-reared A. saxatilis has been
exhaustively described by Alshuth et al. (1998). This study identified
pigmentation, pelvic fin size, and the pectoral fin rays as the most useful
characteristics for identifying the larvae of A. saxatilis from the
yellowtail damselfish Microspathodon chrysurus and beaugregory Stegastes
leucostictus. The sergeant major larva has a smaller and less pigmented fin
and more heavily pigmented dorsal and pelvic fins.
Temperature differences may account for regional variation in morphological
traits, particularly size (Molina et al. 2006).
Abudefduf saxatilis is not reported to exhibit significant tolerance or intolerance for hypo- or hypersaline conditions.
The Seargeant major feeds on an unusually wide variety of
benthic algae, small crustaceans, colonial anemones, copepods, pelagic
tunicates, invertebrate larvae, and small fishes (Randall 1996).
Juvenile Abudefduf saxatilis may take part at
cleaning stations for the sea turtle Chelonia mydas with the doctorfish,
Acanthurus chirurgus, and the blue tang, Acanthurus coeruleus. These fish
inspect the hard shell and the soft tissues of the removing algae and
The sergeant major are popular in the aquarium trade.
Alshuth SR, Tucker JW, and J Hateley. 1998. Egg and larval development
of laboratory-reared sergeant major, Abudefduf saxatilis (Pisces,
Pomacentridae). Bulletin of Marine Science 62:121-133.
Fish Base (a). Abudefduf saxatilis Seargeant major. Species summary. Available online.
Fish Base (b). Abudefduf saxatilis Seargeant major. Synonymy. Available online.
FMNH. Ichthyology at the Florida Museum of Natural History. Available online.
Foster SA. 2004. Diel and lunar patterns of reproduction in the Caribbean
and Pacific sergeant major damselfishes Abudefduf saxatilis and A. troschelii. Marine Biology 95:333-343.
ITIS. Integrated Taxonomic Information System. Available online.
Lindeman KC and DB Snyder. 1999. Nearshore hardbottom fishes of
southeast Florida and effects of habitat burial caused by dredging. Fisheries
Medeiros PR, Grempel RG, Souza AT, Ilarri MI, and CLS Sampaio. 2007. Effects of recreational activities on the fish assemblage
structure in a northeastern Brazilian reef. Pan-American Journal of Aquatic
Molina WF, Shibatta OA, and PM Galetti, Jr. 2006. Multivariate
morphological analyses in continental and island populations of Abudefduf
saxatilis (Linneaeus) (Pomacentridae, Perciformes) of western Atlantic.
Panama-American Journal of Aquatic Science 1:49-56.
Randall JE. 1996. Caribbean Reef Fishes, Third Edition, TFH Publications, Neptune City, NJ. 512 p.
Robertson DR, Schober UM, and JD Brawn. 1993. Comparative variation
in spawning output and juvenile recruitment of Caribbean reef fishes. Marine
Ecology Progress Series 94:105-113.