Saddleback clownfish

Saddleback clownfish
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Superclass:	Osteichthyes
Class:	Actinopterygii
Order:	Perciformes
Family:	Pomacentridae
Subfamily:	Amphiprioninae
Genus:	Amphiprion
Species:	A. polymnus
Binomial name
Amphiprion polymnus (Linnaeus, 1758)[1]

Amphiprion polymnus, also known as the saddleback clownfish or yellowfin anemonefish, is a Marine fish belonging to the family Pomacentridae which gathers clownfishes and damselfishes.^[2]

Description

The Saddleback clownfish is a small sized fish which grows up to 13 centimetres (5.1 in). Its body has a stock appearance, oval shape, compressed laterally and with a round profile.^[3]

Color ranges from dark brown to yellow orange with a thick white bar located just behind the eyes. A large white abbreviated saddle shape or slanted white bar across the middle of the fish's body makes it quite obvious to see how it got the name Saddleback.^[4] In some varieties, typically those specimens initially associated with H. crispa anemone,^[4] the saddle shape may extend up onto the fish's Dorsal fin with a third white bar or margin located across the caudal peduncle (pictured in taxobox).

Melanistic variation has also been partially correlated with the fish's host anemone. Specimens associated with H. crispa tend to be darker than those associated with S. haddoni. Aquarium specimens have been observed becoming lighter or darker after accepting a new host anemone species, sometimes within a few hours.^[4] The external edge of the caudal and the anal fins are underlined with a white line. The snout and the pectoral fin are in any case of color variation orange yellow to brownish orange.^[5]

Distribution

The Saddleback clownfish is found in the center of the Indo-Pacific area.^[6]

Habitat

A group of saddleback anemonefish over their carpet anemone home from East Timor.

Adults inhabit silty lagoons and harbour areas in depth range from 2 to 30 metres (6.6 to 98.4 ft).^[7] Like most clownfish, they are most often observed living in a symbiotic relationship with a host anemone for protection and in the wild are most often seen in association with Stichodactyla haddoni (Saddle carpet anemone) or Heteractis crispa (Sebae anemone^[5]).

Feeding

This anemonefish is omnivorous and its diet is based on zooplankton, small benthic crustaceans and algae.^[8]

Behaviour

Amphiprion polymnus has a diurnal activity. It is protrandous hermaphrodite, which means the male can change into a female during his life, and lives in harem in which an established dominance hierarchy manages the group and keeps individuals at a specific social rank.

It is also an aggressive, territorial animal and it is completely dependent from its sea anemone which it uses as a shelter for the group and for the nest.

The associative relationship that binds the clownfish and the sea anemone is called mutualism. On one hand, the fish can live within the sea anemone's tentacles and uses it as a shelter because it has developed a thin layer of mucus which covers its body as a protection against the stinging anemone's tentacles. On the other hand, the presence of the clownfish can be interpreted as a lure to attract the anemone's prey close to the tentacles. The clownfish can also defend the anemone against some reef fishes which could eat the tentacles such as butterflyfishes.^[5]

The male and female saddleback clownfish are almost equal in size while for the other species of clownfishes females are the biggest. Both species of sea anemone, which the Saddleback clownfish is in association with, are known to bury themselves when they are under stress. In that case, the clownfish is not able to hide in the reef as would have done another species of clownfish, so it has adapted itself by having males as big as the females to limit the predation.^[9]

Captivity

To be kept in an aquarium this species will do best in tanks of at least 30 US gallons (110 l) or larger, preferably aquascaped with live rock to allow multiple choices for hiding places. They should be fed small amounts of food, such as staple marine flake food with occasional frozen mysis shrimp or other small crustacean, two to three times per day.

The protection of a host anemone is not required in an aquarium and attempting to keep either of the species of anemones commonly associated with this clownfish in a captive aquarium environment is not recommended, even for experienced aquarists. This is due to the poor survival rate of wild collected specimens and the overall shortened lifespans these normally centarian organisms often experience in captivity.

See also

Clownfish Coral reef Fish

External links

Wikimedia Commons has media related to Amphiprion polymnus.

Wikispecies has information related to: Amphiprion polymnus

• "Amphiprion polymnus". Integrated Taxonomic Information System. Retrieved 23 August 2007. 
• About.com Library Article
• Field Guide To Anemone Fishes And Their Host Sea Anemones

References