Family: POMACENTRIDAE, Night-Sergeants, Garibaldis, Damselfishes, Sergeant-Majors, Gregories, Chromis
NIGHT-SERGEANTS, GARIBALDIS, DAMSELFISHES, SERGEANT-MAJORS, GREGORIES, CHROMIS
Damselfishes are small (to 35 cm), elongate to ovoid, compressed fishes; 1 pair of nostrils (in neotropical genera); mouth small, protrusible, opens at front; jaw teeth conical, incisors or brush-like; no teeth on roof of mouth; gill rakers small, usually < 35-40; a single continuous dorsal fin, XII-XIV, 10-17 in the neotropics (up to XVII, 21 in other regions), base of the spinous part longer than the soft part; anal fin II (rarely III), 10-14; caudal fin concave to forked; scales are moderately large and rough; body scaled, head largely scaled, as are the basal parts of the median fins; lateral line incomplete or interrupted.
Damselfishes are one of the most abundant groups of reef fishes. Most inhabit the tropics, but a number of species live in cooler temperate waters. They display remarkable diversity with regards to habitat preference, feeding habits, and behaviour. Coloration is highly variable ranging from drab hues of brown, grey and black to brilliant combinations of orange, yellow, and neon blue. A number of species have juvenile stages characterized by a yellow body with bright blue stripes crossing the upper head and back. Most damselfishes are territorial, particularly algal-feeding species such as Stegastes. They zealously defend their small plot against all intruders regardless of size. Damsels exhibit a highly stereotyped mode of reproduction in which one or both partners clear a nest site on the bottom and engage in courtship displays of rapid swimming and fin extension. Males generally guard the eggs which are attached to the bottom by adhesive strands. The eggs hatch within about 2-7 days and the fragile larvae rise to the surface. They develop in the ocean for periods which vary between about 10-50 days, depending on the species. Eventually the young fish settle to the bottom and their largely transparent bodies quickly assume the juvenile coloration. Damselfishes feed on a wide variety of plant and animal material. Generally, the drab-colored species feed mainly on algae, whereas many of the brightly patterned species and also members of the genus Chromis obtain their nourishment from current-borne plankton. Past authors have used the generic names Pomacentrus and Eupomacentrus for the eastern Pacific species now placed in Stegastes. The family was recently reviewed by Allen (1991).
The damselfish family Pomacentridae occurs worldwide in tropical and temperate seas. Approximately three-fourths of the 384 known species from 29 genera are found in the Indo-West Pacific region where they are common inhabitants of coral reefs. In the eastern Pacific 24 species from 7 genera have been reported, all of which are endemic to this region, as are 2 of the genera; 22 are found in the tropical area covered here.