The Philippine Butterflyfish, Chaetodon adiergastos, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of butterflyfish

Butterflyfish

The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae; the bannerfish and coralfish are also included in this group. Found mostly on the reefs of the Atlantic, Indian and Pacific Oceans, there are approximately 120 species in 10 genera...

 (family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Chaetodontidae). It is found in the western Pacific, from the Ryukyu Islands

Ryukyu Islands

The , also known as the , is a chain of islands in the western Pacific, on the eastern limit of the East China Sea and to the southwest of the island of Kyushu in Japan. From about 1829 until the mid 20th century, they were alternately called Luchu, Loochoo, or Lewchew, akin to the Mandarin...

 and Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

 to Java

Java

Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...

 and northwestern Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

.

It grows to a maximum length of 20 cm (nearly 8 in). The body is white with diagonal brown stripes on the sides. The dorsal

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

, caudal, anal and pelvic fins are yellow. There are rounded broad black bands on the face, covering the eye, but not continuous from one side of the body to the other but with a separate black spot centered on the forehead.

It belongs to the large subgenus

Subgenus

In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...

 Rabdophorus which might warrant recognition as a distinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

. In this group, it appears to belong to a loose group including such species as the Black Butterflyfish

Black butterflyfish

The Black Butterflyfish is a species of butterflyfish .-References:*...

 (C. flavirostris), Diagonal Butterflyfish

Diagonal butterflyfish

The Diagonal Butterflyfish , also known as the Red Sea Raccoon Butterflyfish, is a species of butterflyfish . It is found in the Red Sea only....

 (C. fasciatus), Raccoon Butterflyfish

Raccoon butterflyfish

The raccoon butterflyfish, Chaetodon lunula, also known as the crescent-masked butterflyfish or lunule butterflyfish, is a species of butterflyfish . It is found in the Indo-Pacific region and in the southeast Atlantic...

 (C. lunula) and perhaps also the unusual Red-tailed Butterflyfish (C. collare). Although the coloration of this group varies quite a lot, they are all largish butterflyfishes with an oval outline, and most have a pattern of ascending oblique stripes on the flanks. Except in the Red-tailed Butterflyfish, there is at least a vestigial form of the "raccoon

Raccoon

Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...

" mask, with a white space between the dark crown and eye areas.

The Philippine Butterflyfish is found in coral reef

Coral reef

Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s at depths of 3-25 m and occurs in pairs or groups, usually near soft coral. Juveniles are solitary and found on shallow protected reefs or in estuaries.