- Common Name
- sergeant major
- Genus Species
- Abudefduf saxatilis
- Dorsal spines (total): 13 and 13; Dorsal softrays (total): 12 and 13; Anal spines: 2 and 2; Anal soft-rays: 10 and 12. Yellow to gray dorsal, shading to white ventral, with 5 distinct vertical black bars. Faint sixth bar may be present along caudal peduncle. Adult male exhibits dark blue to dark gray background tonality during the mating season, with the black bars concurrently less conspicuous.
- 10.2 to 15.2 cm (4 to 6 in.) avg.; 22.9 cm (9 in.) max
- 200 g (6.4 oz.) max
- Algae, invertebrate larvae, small crustaceans, and small fish
- Species exhibits dioecism. Fertilization is external. Spawns year-round. Species creates nesting site which the male guards.
- Western Atlantic: Rhode Island (seasonal extreme) to Uruguay (seasonal extreme)
Eastern Atlantic: Mid-Atlantic islands, Cape Verde south to Angola
Western Pacific: Great Barrier Reef, Australia
- 1 to 15 meters (3 to 49 ft) in tropical & sub-tropical marine and/or brackish coastal waters
- Global: No data
- IUCN: Not listed
CITES: Not listed
USFWS: Not listed
- Adults will often form large feeding aggregations, sometimes containing several hundred individuals.
- Adult males adopt a bluish hue while guarding the nesting site.
- This species is commonly referred to as "sergeant major" as it exhibits five black bars – resembling the insignia of said rank in the military services.
- Male sergeant majors exhibit a dark blue to dark gray background tonality during the breeding season. Beyond that, sexual dimorphism is minimal; thereby making it rather difficult to distinguish male from female via casual observation.
- Male sergeant majors guard the eggs during the four days incubation period prior to hatching.
- For more information about bony fishes, explore the Bony Fishes InfoBook.
Ecology and Conservation
The current global trend of coral reef depletion could ultimately effect severe change to sergeant major populations; however, there are no currently identified significant threats to the species.
Bond, Carl E. Biology of Fishes - Second Edition. Saunders College Publishing, 1996.
Humann, Paul. Reef Fish Identification - Florida, Caribbean, Bahamas. New World Publications, Inc., 1992.