Pearlscale butterflyfish
Encyclopedia
The Pearlscale Butterflyfish (Chaetodon xanthurus) is a species
of butterflyfish
(family
Chaetodontidae) also known as Yellow-tailed Butterflyfish or Philippines Chevron Butterflyfish (the Chevron Butterflyfish
is an unrelated species of Chaetodon). It is found on or around the reef
s of the western Pacific Ocean
from Indonesia
and the Philippines
north to the Ryukyu Islands
.
In the wild adults can grow to 15 cm with no discernible differences between males and females. The body is pearly white and the scales have black edges, giving the sides a more cross-hatched pattern instead of the clear chevrons in related species. The hind parts are orangey-yellow, the base of the caudal fin is white. The head is darker than the body and bears the characteristic pattern of its lineage, consisting of vertical
black eyestripes and a black white-rimmed crown spot.
They are found in clear coastal to outer reef
slopes and drop-offs, often around Acropora
staghorn corals. These fish have a peaceful temperament and in the wild are found either alone, in pairs, or in small groups, however they are territorial towards similar-looking species and may harass them. Due to its attractive colors, the Pearlscale Butterflyfish is a well-known aquarium
fish. A 50 gallon aquarium is the minimum size recommended for them, with a water temperature of between about 74 and 80° F
. Although they can be aggressive at times, they are delicate and peaceful tankmates are required for this fish to thrive in an aquarium. They may be compatible with other butterflyfishes that have a different color pattern, but there is no guarantee that their relationship will always be peaceful. When adding more than one to a tank they have to be added simultaneously, and lots of "living rock
" with shelters available for them to hide helps to reduce stress.
In the wild they feed on algae
, soft coral polyps and small benthic invertebrate
s, so therefore along with other coral-eating Chaetodon species they can wreak havoc on living corals in the aquarium. They should be fed a variety of foods that can include mysid shrimp, brine shrimp
, krill
, spirulina
and foods containing algae.
(C. mertensii), Eritrean
(C. paucifasciatus) and Seychelles butterflyfish
es (C. madagaskariensis), which are closer related among each other that any is to C. xanthurus.Fessler & Westneat (2007), Hsu et al. (2007)
The "crowned" Chaetodon are a clearly recognizable clade
, but their further relationships are otherwise less clear. They were often placed in the subgenus
Exornator, or considered a distinct subgenus Rhombochaetodon. According to various DNA sequence
studies, some older and more singular lineages. These include species such as the Asian Butterflyfish (C. argentatus), the Blue-striped Butterflyfish (C. fremblii) and Burgess' Butterflyfish (C. burgessi). C. burgessi is in fact so peculiar that it was placed in a monotypic
subgenus Roaops. But recognition of this would probably result in several other small or monotypic subgenera becoming justified, and the older Rhombochaetodon would be the more conveniently apply to the entire radiation.
But the expanded group is of unclear relationships to species like the Speckled Butterflyfish
(C. citrinellus) and the Four-spotted Butterflyfish (C. quadrimaculatus). These might be members of the subgenus Exornator – the lineages around the Spot-banded Butterflyfish (C. punctatofasciatus) – and C. citrinellus certainly looks somewhat similar to these. Yet phylogenetically, their position towards Rhombochaetodon is unresolved, and ultimately it might be better to merge both Rhombochaetodon and Roaops in Exornator. If the genus Chaetodon
is split up, Exornator might become a subgenus of Lepidochaetodon or a separate genus.
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) also known as Yellow-tailed Butterflyfish or Philippines Chevron Butterflyfish (the Chevron Butterflyfish
Chevron butterflyfish
Not to be confused with Chaetodon trifasciatus . See also Chaetodon tricinctus and Three-banded Butterflyfish....
is an unrelated species of Chaetodon). It is found on or around the reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s of the western Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
from Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
and the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
north to 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...
.
In the wild adults can grow to 15 cm with no discernible differences between males and females. The body is pearly white and the scales have black edges, giving the sides a more cross-hatched pattern instead of the clear chevrons in related species. The hind parts are orangey-yellow, the base of the caudal fin is white. The head is darker than the body and bears the characteristic pattern of its lineage, consisting of vertical
Vertical direction
In astronomy, geography, geometry and related sciences and contexts, a direction passing by a given point is said to be vertical if it is locally aligned with the gradient of the gravity field, i.e., with the direction of the gravitational force at that point...
black eyestripes and a black white-rimmed crown spot.
Ecology in the wild and the aquarium
Pearlscale butterflyfish are a diurnal species and usually found at depths below 15 m (49 ft).They are found in clear coastal to outer reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
slopes and drop-offs, often around Acropora
Acropora
Acropora is a genus of scleractinian coral in the Phylum Cnidaria. Some of its species are known as table coral, elkhorn coral and staghorn coral. There are currently 149 described species...
staghorn corals. These fish have a peaceful temperament and in the wild are found either alone, in pairs, or in small groups, however they are territorial towards similar-looking species and may harass them. Due to its attractive colors, the Pearlscale Butterflyfish is a well-known aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
fish. A 50 gallon aquarium is the minimum size recommended for them, with a water temperature of between about 74 and 80° F
Fahrenheit
Fahrenheit is the temperature scale proposed in 1724 by, and named after, the German physicist Daniel Gabriel Fahrenheit . Within this scale, the freezing of water into ice is defined at 32 degrees, while the boiling point of water is defined to be 212 degrees...
. Although they can be aggressive at times, they are delicate and peaceful tankmates are required for this fish to thrive in an aquarium. They may be compatible with other butterflyfishes that have a different color pattern, but there is no guarantee that their relationship will always be peaceful. When adding more than one to a tank they have to be added simultaneously, and lots of "living rock
Living rock
Living rock can refer to dwarf succulent plants resembling stones, especially of the genera:*Ariocarpus*Astrophytum*Aztekium*Epithelantha*Geohintonia*Lithops*Lophophora*Obregonia*Turbinicarpus*Strombocactus...
" with shelters available for them to hide helps to reduce stress.
In the wild they feed on algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, soft coral polyps and small benthic invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, so therefore along with other coral-eating Chaetodon species they can wreak havoc on living corals in the aquarium. They should be fed a variety of foods that can include mysid shrimp, brine shrimp
Brine shrimp
Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period...
, krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...
, spirulina
Spirulina
Spirulina may refer to:* Spirulina , a health-food supplement* Spirulina , a cyanobacterium group* Ochthephila spirulina, species of gastropod in the Hygromiidae family...
and foods containing algae.
Systematics
C. xanthurus is one of the "crowned" butterflyfishes. These form a group of largely allopatric species sharing the overall color pattern of dark forward-pointing chevrons on silvery hues, (usually) a black-and-white crown spot and yellow to red hindparts to a stunning degree; they differ in the exact combination of hues and some small pattern details. Other members of this lineage are the AtollAtoll butterflyfish
The Atoll Butterflyfish, Chaetodon mertensii, is a species of butterflyfish . It is found in the Pacific Ocean from the Ryukyu Islands to the Philippines and extending to Lord Howe Island, Rapa Iti and the Tuamotus....
(C. mertensii), Eritrean
Eritrean butterflyfish
The Eritrean Butterflyfish or Crown Butterflyfish, Chaetodon paucifasciatus, is a species of butterflyfish . It is essentially just known from the Red Sea and the Gulf of Aden, but has been reported from East Africa....
(C. paucifasciatus) and Seychelles butterflyfish
Seychelles butterflyfish
The Seychelles Butterflyfish, Chaetodon madagaskariensis, is a species of butterflyfish . It is found in the Indian Ocean from eastern Africa east to Cocos-Keeling Islands and Christmas Island, north to Sri Lanka...
es (C. madagaskariensis), which are closer related among each other that any is to C. xanthurus.Fessler & Westneat (2007), Hsu et al. (2007)
The "crowned" Chaetodon are a clearly recognizable clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
, but their further relationships are otherwise less clear. They were often placed in the 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...
Exornator, or considered a distinct subgenus Rhombochaetodon. According to various DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
studies, some older and more singular lineages. These include species such as the Asian Butterflyfish (C. argentatus), the Blue-striped Butterflyfish (C. fremblii) and Burgess' Butterflyfish (C. burgessi). C. burgessi is in fact so peculiar that it was placed in a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
subgenus Roaops. But recognition of this would probably result in several other small or monotypic subgenera becoming justified, and the older Rhombochaetodon would be the more conveniently apply to the entire radiation.
But the expanded group is of unclear relationships to species like the Speckled Butterflyfish
Speckled butterflyfish
Chaetodon citrinellus is a species of butterflyfish . It is commonly known as the Speckled Butterflyfish or Citron Butterflyfish...
(C. citrinellus) and the Four-spotted Butterflyfish (C. quadrimaculatus). These might be members of the subgenus Exornator – the lineages around the Spot-banded Butterflyfish (C. punctatofasciatus) – and C. citrinellus certainly looks somewhat similar to these. Yet phylogenetically, their position towards Rhombochaetodon is unresolved, and ultimately it might be better to merge both Rhombochaetodon and Roaops in Exornator. If the genus Chaetodon
Chaetodon
Chaetodon is a tropical fish genus in the family Chaetodontidae. Like their relatives, they are known as "butterflyfish". This genus is by far the largest among the Chaetodontidae, with about 90 living species included here, though most might warrant recognition as distinct genera.Several subgenera...
is split up, Exornator might become a subgenus of Lepidochaetodon or a separate genus.