Squarespot Anthias

There are many species of anthias – these small, brightly colored fishes usually live in huge schools. Within these large groups, are smaller units called harems. Each harem is led by the largest, brightest male. His harem consists of smaller males, many females, and juveniles.

• Size

  7.9 inches (20 cm)

• Diet

  Zooplankton

• Range

  Pacific Ocean

• Habitat

  Reefs at depth from 33-591 feet (10-180 m)

Physical Characteristics

• Comes in a variety of colors, including red, pink, orange, yellow and purple.
• Male characterized by a reddish pink body with a square violet -colored spot on side and an elongated third dorsal spine. Female is less colorful than the male, often solid yellow or orange with no other markings.
• Maximum size is about 7.8 inches (20 cm).
• Bullet-shaped and darts about when feeding or defending territory.

Animal Fun Fact

All squarespot anthias begin life as female – some individuals then change sex and become male as adults.

Diet / Feeding

• Diet consists of zooplankton.

Range / Habitat

• Occurs throughout the Pacific Ocean from Indonesia to Samoa, the Ryukyu Islands, Rowley Shoals and New Caledonia, as well as throughout Micronesia.
• Found around reefs at depths from 33-591 feet (10-180 m).
• Lives in large groups, with few males and several dozen females and juveniles. These groups are found in areas of branching hard corals where they take shelter.
• Active during the day and will spend most of their time swimming above coral reefs and feeding on plankton.

Reproduction & Growth

• Sequential hermaphrodite: can change sex from female to male.
• Begins life as a female. Due to environmental or social factors, such as a male dying, females can become males.
• Sex change ensures there will always be a male and a female to reproduce.
• A female replacing the dominant male in a harem’s hierarchy is capable of changing her sex to male in a period of 2-3 weeks.

Conservation Status

• “Least Concern” on the IUCN Red List.

Additional Information

• Protogynous hermaphrodite: can change sex from female to male.
• Begins life as female. Due to environmental or social factors, such as male dying, some females can become males.
• Sex change ensures there will always be a male and a female to reproduce.
• Female replacing dominant male in a harem’s hierarchy is capable of changing her sex to male in a period of 2-3 weeks.
• Forms huge schools actually made up of small coexisting social harems. Each harem usually led by largest most colorful male. Includes several smaller less dominant males, a group of females and juvenile fish.
• Dominant male constantly defends its place in the group’s hierarchy by challenging lesser males and males from neighboring harems.

Sources

• www.fishbase.org
• www.masla.com/anthias.html
• Reef Fish Identification – Tropical Pacific.  Allen, G.; Steene, R.; Humann, P. and Deloach, N., pgs. 138, 143