Green damselfish

The green damselfish (Abudefduf abdominalis),^[3] also known as the Hawaiian sergeant major, is a non-migratory fish of the family Pomacentridae. This fish also goes by the name maomao^[4] It occurs in the Pacific Ocean in the vicinity of the Hawaiian Islands, Midway Island and Johnston Atoll.^[1] It can grow to a maximum total length of 30 centimetres (12 in).

Green damselfish
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Blenniiformes
Family:	Pomacentridae
Genus:	Abudefduf
Species:	A. abdominalis
Binomial name
Abudefduf abdominalis (Quoy & Gaimard, 1825)
Synonyms[2]
Glyphisodon abdominalis Quoy & Gaimard, 1825

Adults of the species are typically found in quiet waters with rocky bottoms in inshore and offshore reefs at a depth of 1 to 50 m (3 ft 3 in to 164 ft 1 in), although juveniles may sometimes be found in surge pools. It is a benthopelagic species, with adults being known to form schools. The species feeds on a variety of algae and zooplankton. It is known to be used as a food source for humans in Hawaii.^[2] It occasionally appears in the aquarium trade.^[1]

Breeding

Abudefduf abdominalis is oviparous, with distinct pairing occurring during breeding. Abudefduf abdominalis is known for being a species of fish that are polygamous during their breeding time.^[5] Eggs are demersal and adhere to the substrate, with males guarding and aerating the eggs. Breeding cycles depend on the availability of food.^[6] It is known to hybridise with Abudefduf vaigiensis which has been introduced to Hawaiian coastal waters.^[7] Abudefduf abdominalis are capable of spawning year round, though are most active during mid December all through July.^[8] To enchant the female of the species, males will take what are called "nuptial colors" like dark blue and have light yellow bars and will perform various dances to attract a mate. Such dances include swimming in zig-zag patterns, swimming in loops, or floating head down.^[9]

Appearance

These fishes can range from 7 inches to 9 inches on average. ^[10] The juveniles start out with a yellow tinge, which turns greenish white as they mature. The rear fin has a black marking.^[10] During breeding the males turn blue and their black bars begin to fade into a gray instead. ^[8]

Diet

These fish are known to nibble on zooplankton, Copepods usually^[8] and on occasion they'll also eat algae.^[10]

Predators

Some fish that prey on this species include but are not limited to the Milletseed Butterflyfish, Racoon Butterflyfish, and the Black Triggerfish.^[11] Some predators like the Milletseed Butterflyfish will travel close behind divers to find a Hawaiian Sergeant nest and feast on the eggs.^[9]