Pomacentridae

Pomacentridae is the family of Damselfishes and Clownfishes. They are mainly but a few species can be found in freshwater or brackish water environments (e.g. Neopomacentrus aquadulcis, N. taeniurus, Pomacentrus taeniometopon, Stegastes otophorus). They are known for their tough constitution and territorial behavior. Many are brightly colored and therefore popular for keeping in aquariums.

This family includes about 360 species in about 29 families. Of these species, two families are commonly called Clownfishes, while members of another family (e.g. Pomacentrus) are commonly called Damselfish.

Etymology

The name of this family is derived from the Greek words; poma which can be roughly translated as lid and refers to the gill cover, kentron is Greek for spine. The name refers to the serrated edges of the operculum bones that many members of this family possess.

Distribution and Environment

Pomacentridae can be found in tropical seas, only a few species occur in temperate temperatures (e.g. Hypsypops rubicundus). Most species can be found in or near the coral reefs in the Indo-West Pacific (from east Africa to Polynesia). The area from the Philippines to Australia contains the largest concentration of species. The remaining species are found in the Atlantic Ocean and the Eastern Pacific Ocean. Some species occur in freshwater or the brackish water of the estuaries.

Most members of the family live in shallow water, from 2 to 15 meters, although some species (e.g. Chromis abyssus) can be found at greater depths than 100 meters. Most species are specialists and live in specific parts of the reef, such as sandy lagoons, steep reefs or areas exposed to strong waves. In general, the coral is used for shelter and many species can only survive near coral.

The bottom-dwelling species are territorial, occupying and defending a portion of the reef, often centered around their refuge. By keeping other species away, some Pomacentridae ensure that a thick layer of algae can grow within their territory, which is why they are nicknamed Farmerfish in English.

Characteristics

Pomacentridae have a rounded to elongated body shape that is often laterally compressed. They have an interrupted or incomplete lateral line and typically have a single nostril on each side (some species of Chromis and Dascyllus have two on each side). They have small to medium sized ctenoid scales (scales with serrated edges). They have one or two rows of teeth, which are conical or spatula-shaped.

They display a wide range of colors, including bright shades of yellow, red, orange and blue, although some are relatively dull with brown, black or gray. The young are usually different and brighter colored than the adults.

Pomacentridae are omnivores or herbivores and feed on algae, plankton and small bottom-dwelling invertebrates, depending on their habitat. Only a small number of families, such as the Cheiloprion, eat the corals among which they live.

They also form symbiotic bonds with cleaner gobies of the genus Elacatinus, allowing the gobies to eat the ectoparasites from their bodies.

Propagation

Before mating, the males clear an area of algae and invertebrates to make a nest. They perform an entire ritual to court the females, which may include rapid bursts of speed, chasing or sipping the females, hovering stationary, or spreading the fins widely. After being attracted to the spawning site, the female lays a string of sticky eggs that stick to the substrate. The male swims behind the female as she lays her eggs and fertilizes them externally. Depending on the species, the clutch contains from 50 to 1000 eggs.

The male guards the nest for 2 to 7 days before the eggs hatch. The transparent larvae are 2 to 4 mm in size. The larvae undergo a pelagic phase (floating through the open sea) which can last a week or even longer than a month. When they arrive at a suitable habitat, the young settle there and acquire their juvenile colors.

In captivity, Pomacentridae can live up to about 18 years, but in the wild they usually do not live longer than 10 to 12 years.

CC BY-SA 4.0.Based on a work on Wikipedia.org.