Asian arowana
Encyclopedia
The Asian arowana comprises several varieties of freshwater
fish
in the genus Scleropages
. Some sources differentiate these varieties into multiple species
, while others consider the different strains to belong to a single species, Scleropages formosus. They have several other common names, including Asian bonytongue, dragon fish, and a number of names specific to different varieties.
Native to Southeast Asia
, Asian arowanas inhabit blackwater river
s, slow-moving waters flowing through forested swamps and wetland
s. Adults feed on other fish, while juveniles feed on insect
s.
These popular aquarium
fish have special cultural
significance in areas influenced by Chinese culture. The name dragon fish stems from their resemblance to the Chinese dragon
. This popularity has had both positive and negative effects on their status as endangered species
.
and are incapable of surviving in the ocean. Therefore, their spread throughout the islands of southeast Asia suggests they diverged from other osteoglossids before the continental breakup
was complete. Genetic studies have confirmed this hypothesis, showing that their ancestor of the Asian arowanas diverged from the ancestor of the Australian arowanas, S. jardinii and S. leichardti, about 140 million years ago, during the Early Cretaceous
period. This divergence took place in the eastern margin of Gondwanaland, with the ancestors of Asian arowanas carried on the Indian subcontinent
or smaller landmasses into Asia. The morphological
similarity of all Scleropages species shows that little evolution
ary change has taken place recently for these ancient fish.
The first description of these species was published between 1839 and 1844 (1844 is the date commonly cited) by German naturalists
Salomon Müller
and Hermann Schlegel
, under the name Osteoglossum
formosum, although later this species was placed in Scleropages with the name S. formosus.
Several distinct, naturally occurring colour varieties are recognised, each found in a specific geographic region. They include the following:
In 2003, a study was published which proposed breaking S. formosus into four separate species. This classification was based on both morphology
and genetics
, and includes the following species:
Other researchers dispute this reclassification, arguing that the published data are insufficient to justify recognizing more than one Southeast Asian species of Scleropages.
Asian arowanas grow up to 90 cm (35 in) total length
. Like all Scleropages, Asian arowanas have long bodies; large, elongate pectoral fins; dorsal
and anal fins located far back on the body; and a much larger caudal fin than that of their South America
n relative, the silver arowana
, Osteoglossum bicirrhosum. The mouth is oblique with a very wide gape. The prominent lower jaw has two barbel
s at its tip. The gill raker
s are stout. Asian arowanas bear teeth on many bones of the mouth, including the jaws, vomer, palatines, pterygoids, parasphenoid, and tongue.
Asian arowana scales are large, cycloid, and, in some varieties, metallic coloured, with a distinctive mosaic
pattern of raised ribs. The lateral scales are arranged in horizontal rows numbered from the most ventral (first level) to the most dorsal (fifth level), with dorsal scales designated the sixth level.
Asian arowanas are distinguished from Australian congenerics S. jardinii
and S. leichardti
by having fewer (21-26) lateral line
scales (versus 32-36 for the Australian species), longer pectoral and pelvic fins, and a longer anterior snout.
Green arowanas are dark green on the back, silvery or golden green on its sides, and silvery or whitish on its ventral surface, with dark greenish or bluish patches visible through the lateral scales. In mature fish, the top of the eye and the head behind the eye are bright emerald.
Both grey-tailed and yellow-tailed silver Asian arowanas are dark grey on the back and silver on the sides, with dark ring patches on the lateral scales and a silvery or whitish belly. In yellow-tailed specimens, the fin membranes are yellowish with dark grey rays. In grey-tailed specimens, the fins are uniform dark grey.
Mature red-tailed golden arowanas have brilliant metallic gold lateral scales, gill covers
, bellies, and pectoral and pelvic fin membranes, although the back is dark. In juveniles the areas destined to develop golden colour start out metallic silver. The anal fin and the bottom portion of the caudal fin are light brown to dark red.
Mature gold crossback arowanas are distinguished from the red-tailed golden arowanas by having metallic gold crossing the back completely. This variety also lacks the reddish fins of the red-tailed golden.
In mature super red arowanas, the gill covers, lateral scales, and fin membranes of these fishes are metallic red, with the exact hue varying from gold-tinged to deep red. The back is dark brown. In juveniles, the darker the dorsal colouration, the deeper the red will be on maturity.
s. They are slow to reach sexual maturity and difficult to breed in captivity; successful spawning
s typically take place in large outdoor ponds rather than in aquaria
.
Two breeders reported success using a garden pond measuring 18 feet (5.5 m) by 18 feet (5.5 m) by 3.5 feet (1.1 m) deep, with pH
maintained between 6.5 and 7.0. The fish were over five years old. The successful harvest took place after the third spawning; in the first two spawnings, the male swallowed the eggs, possibly due to improper water quality.
by the 2006 IUCN Red List
, with the most recent evaluation taking place in 1996. International trade in these fishes is controlled under the Convention on the International Trade in Endangered Species of Wild Flora and Fauna
(CITES), under which it was placed on Appendix I, the most restrictive category, in 1975. S. formosus is one of only eight fish species listed on Appendix I. There are a number of registered CITES breeders in Asia and the specimens they produce can be imported into several nations. Other nations restrict or prohibit possession of Asian arowanas; for example, the United States
has listed this species under the Endangered Species Act
, and therefore it cannot be possessed in that country without a permit.
Declining habitat
is a major threat. For example, Asian arowanas are now uncommon in the Malay Peninsula
, where they were once widely distributed, due to environmental destruction. Inclusion in the IUCN Red List was originally based not on biological reasons but on practical ones: though widely distributed throughout southeast Asia, they have been harvested heavily by aquarium collectors. However, habitat loss is likely a greater threat than aquarium collecting.
There is no recent evaluation of conservation status
by IUCN. Additionally, considering the current confusion as to number of species as well as the wide distribution, conservation status needs to be reconsidered. All strains are probably endangered, but some (notably the super red and red-tailed golden) more critically than others.
The Asian arowana's high value as aquarium
fish has impacted its conservation
. Its popularity has soared since the late 1970s, and hobbyists may pay thousands of U.S. dollars
for one of these animals.
Beginning in 1989, CITES began allowing Asian arowanas to be traded, provided certain criteria were met, most notably that they were bred in captivity on a fish farm
for at least two generations. The first of these farms was in Indonesia
. Later, the Singapore government
's Agri-food and Veterinary Authority (then called the Primary Production Department) and a local fish exporter collaborated in a captive breeding
program. Asian arowanas legally certified by CITES for trade became available from this program in 1994.
Captive-bred arowanas that are legal for trade under CITES are documented in two ways. First, fish farms provide each buyer with a certificate of authenticity and a birth certificate. Second, each specimen receives an implanted microchip
, called a Passive Integrated Transponder (PIT), which identifies individual animals.
Genetic fingerprinting
has been used to assess the genetic diversity
of a captive population at a Singapore
fish farm in order to improve the management of this species. DNA markers that distinguish among different strains and between sexes have been identified, allowing aquaculturists to identify these characteristics in immature animals.
and may be kept with other Scleropages only in a very large aquarium, provided all fish are of similar size. Like other arowana
s, they need a tight-fitting cover to prevent jumping. The water should be well-filtered, soft, and slightly acidic
, and maintained at a temperature of 24–30° C (75–86° F).
Asian arowanas are carnivorous
and should be fed a high-quality diet of meaty food, such as shrimp
and cricket
s. They are surface feeders and prefer to take food in the upper parts of the water column. Aquarists recommend live foods and meaty prepared foods. Examples of appropriate live foods include scorpions
, centipedes
, mealworm
s, cricket
s, shrimp
s, feeder fish
, small frog
s, and earthworm
s. Prepared foods include prawns (shrimp), lean pork, frozen fish food, and pelleted food.
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
in the genus Scleropages
Scleropages
Sceleropages is a genus of freshwater fishes found in Asia and Australia. Six species are currently recognized. All are carnivorous and have great jumping ability. Most are endangered in the wild to some degree. Scleropages species are highly valued as aquarium fish, particularly by those from...
. Some sources differentiate these varieties into multiple 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...
, while others consider the different strains to belong to a single species, Scleropages formosus. They have several other common names, including Asian bonytongue, dragon fish, and a number of names specific to different varieties.
Native to Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, Asian arowanas inhabit blackwater river
Blackwater river
A blackwater river is a river with a deep, slow-moving channel that flows through forested swamps and wetlands. As vegetation decays in the water, tannins are leached out, resulting in transparent, acidic water that is darkly stained, resembling tea or coffee. Most major blackwater rivers are in...
s, slow-moving waters flowing through forested swamps and wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
s. Adults feed on other fish, while juveniles feed on insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s.
These popular 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 have special cultural
Culture
Culture is a term that has many different inter-related meanings. For example, in 1952, Alfred Kroeber and Clyde Kluckhohn compiled a list of 164 definitions of "culture" in Culture: A Critical Review of Concepts and Definitions...
significance in areas influenced by Chinese culture. The name dragon fish stems from their resemblance to the Chinese dragon
Chinese dragon
Chinese dragons are legendary creatures in Chinese mythology and folklore, with mythic counterparts among Japanese, Korean, Vietnamese, Bhutanese, Western and Turkic dragons. In Chinese art, dragons are typically portrayed as long, scaled, serpentine creatures with four legs...
. This popularity has had both positive and negative effects on their status as endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
.
Evolution and taxonomy
Like all members of Osteoglossidae, Asian arowanas are highly adapted to fresh waterFresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
and are incapable of surviving in the ocean. Therefore, their spread throughout the islands of southeast Asia suggests they diverged from other osteoglossids before the continental breakup
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
was complete. Genetic studies have confirmed this hypothesis, showing that their ancestor of the Asian arowanas diverged from the ancestor of the Australian arowanas, S. jardinii and S. leichardti, about 140 million years ago, during the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
period. This divergence took place in the eastern margin of Gondwanaland, with the ancestors of Asian arowanas carried on the Indian subcontinent
Indian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...
or smaller landmasses into Asia. The morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
similarity of all Scleropages species shows that little evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary change has taken place recently for these ancient fish.
The first description of these species was published between 1839 and 1844 (1844 is the date commonly cited) by German naturalists
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
Salomon Müller
Salomon Müller
Dr Salomon Müller was a German naturalist.Müller was the son of a saddler in Heidelberg. In 1823 Müller, along with Heinrich Boie and Heinrich Christian Macklot, was sent by Coenraad Jacob Temminck to collect specimens in the East Indies. Müller visited Indonesia in 1826, New Guinea and Timor in...
and Hermann Schlegel
Hermann Schlegel
Hermann Schlegel was a German ornithologist and herpetologist.-Early life and education:Schlegel was born at Altenburg, the son of a brassfounder. His father collected butterflies, which stimulated Schlegel's interest in natural history...
, under the name Osteoglossum
Osteoglossum
Osteoglossum is a genus of fish in the family Osteoglossidae. The genus contains two species: the silver arowana and the black arowana . They reach almost in length and are restricted to freshwater habitats in tropical South America....
formosum, although later this species was placed in Scleropages with the name S. formosus.
- The green is the most common variety, found in IndonesiaIndonesiaIndonesia , 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...
(KalimantanKalimantanIn English, the term Kalimantan refers to the Indonesian portion of the island of Borneo, while in Indonesian, the term "Kalimantan" refers to the whole island of Borneo....
and SumatraSumatraSumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
), VietnamVietnamVietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
, MyanmarMyanmarBurma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....
, ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, CambodiaCambodiaCambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
, and Malaysia. - The silver Asian (not to be confused with the silver arowanaSilver arowanaThe silver arowana, Osteoglossum bicirrhosum, sometimes spelled arawana, is a freshwater bony fish of the family Osteoglossidae, commonly kept in aquaria...
, Osteoglossum bicirrhosum) is considered part of the green variety by some. It has two subvarieties, the "grey tail silver" or "Pinoh arowana," and the "yellow tail silver," each found in a different part of the island of BorneoBorneoBorneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
in IndonesiaIndonesiaIndonesia , 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...
. - The red-tailed golden is found in northern SumatraSumatraSumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
, Indonesia. - The gold crossback, blue Malayan, or Bukit Merah blue is native to the state of PahangPahangPahang is the third largest state in Malaysia, after Sarawak and Sabah, occupying the huge Pahang River river basin. It is bordered to the north by Kelantan, to the west by Perak, Selangor, Negeri Sembilan, to the south by Johor and to the east by Terengganu and the South China Sea.Its state...
and the Bukit MerahBukit Merah, PerakOne of two towns in the Malaysian state of Perak.- District of Selama, Northern Perak:Bukit Merah is a town and a popular tourist destination. It is famous for the Bukit Merah Laketown Resort.- District of Kinta, Central Perak :...
area in PerakPerakPerak , one of the 13 states of Malaysia, is the second largest state in the Peninsular Malaysia bordering Kedah and Yala Province of Thailand to the north, Penang to the northwest, Kelantan and Pahang to the east, Selangor the Strait of Malacca to the south and west.Perak means silver in Malay...
, Peninsular MalaysiaPeninsular MalaysiaPeninsular Malaysia , also known as West Malaysia , is the part of Malaysia which lies on the Malay Peninsula. Its area is . It shares a land border with Thailand in the north. To the south is the island of Singapore. Across the Strait of Malacca to the west lies the island of Sumatra...
. - The red, super red, blood red, or chili red is known only from the upper part of the Kapuas RiverKapuas RiverThe Kapuas River is a river in the Indonesian part of Borneo island, at the geographic center of Maritime Southeast Asia. At in length, it is the longest river of Indonesia and one of the world's longest island rivers...
and nearby lakes in western Borneo, Indonesia.
In 2003, a study was published which proposed breaking S. formosus into four separate species. This classification was based on both morphology
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
and genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
, and includes the following species:
- Scleropages formosus was redescribed to include the strain known as the green arowana. The gold crossback, which was not part of the study, was included in this species by default, though it was suspected that it was closely related to S. aureus.
- Scleropages macrocephalus described the silver Asian arowana.
- Scleropages aureus described the red-tailed golden arowana.
- Scleropages legendrei described the super red arowana.
Other researchers dispute this reclassification, arguing that the published data are insufficient to justify recognizing more than one Southeast Asian species of Scleropages.
Description
Fish measurement
Fish measurement refers to the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.-Overall length:...
. Like all Scleropages, Asian arowanas have long bodies; large, elongate pectoral fins; 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...
and anal fins located far back on the body; and a much larger caudal fin than that of their South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
n relative, the silver arowana
Silver arowana
The silver arowana, Osteoglossum bicirrhosum, sometimes spelled arawana, is a freshwater bony fish of the family Osteoglossidae, commonly kept in aquaria...
, Osteoglossum bicirrhosum. The mouth is oblique with a very wide gape. The prominent lower jaw has two barbel
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
s at its tip. The gill raker
Gill raker
Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch and are involved with filter feeding tiny prey. They are not to be confused with the gill filaments that compose the bony part of the gill. Rakers are usually present in two rows, projecting from both the...
s are stout. Asian arowanas bear teeth on many bones of the mouth, including the jaws, vomer, palatines, pterygoids, parasphenoid, and tongue.
Asian arowana scales are large, cycloid, and, in some varieties, metallic coloured, with a distinctive mosaic
Mosaic
Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials. It may be a technique of decorative art, an aspect of interior decoration, or of cultural and spiritual significance as in a cathedral...
pattern of raised ribs. The lateral scales are arranged in horizontal rows numbered from the most ventral (first level) to the most dorsal (fifth level), with dorsal scales designated the sixth level.
Asian arowanas are distinguished from Australian congenerics S. jardinii
Gulf saratoga
The gulf saratoga, Scleropages jardinii, is a freshwater bony fish native to Australia and New Guinea, one of two species of fishes sometimes known as Australian arowanas, the other being the saratoga...
and S. leichardti
Saratoga (fish)
The saratoga, Scleropages leichardti, also known as the spotted bonytongue, spotted saratoga, or southern saratoga, is a freshwater bony fish native to Australia. It belongs to the subfamily Osteoglossinae, or arowanas, a primitive group of teleosts. Like all arowanas, it is a carnivorous...
by having fewer (21-26) lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
scales (versus 32-36 for the Australian species), longer pectoral and pelvic fins, and a longer anterior snout.
Green arowanas are dark green on the back, silvery or golden green on its sides, and silvery or whitish on its ventral surface, with dark greenish or bluish patches visible through the lateral scales. In mature fish, the top of the eye and the head behind the eye are bright emerald.
Both grey-tailed and yellow-tailed silver Asian arowanas are dark grey on the back and silver on the sides, with dark ring patches on the lateral scales and a silvery or whitish belly. In yellow-tailed specimens, the fin membranes are yellowish with dark grey rays. In grey-tailed specimens, the fins are uniform dark grey.
Operculum (fish)
The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
, bellies, and pectoral and pelvic fin membranes, although the back is dark. In juveniles the areas destined to develop golden colour start out metallic silver. The anal fin and the bottom portion of the caudal fin are light brown to dark red.
Mature gold crossback arowanas are distinguished from the red-tailed golden arowanas by having metallic gold crossing the back completely. This variety also lacks the reddish fins of the red-tailed golden.
In mature super red arowanas, the gill covers, lateral scales, and fin membranes of these fishes are metallic red, with the exact hue varying from gold-tinged to deep red. The back is dark brown. In juveniles, the darker the dorsal colouration, the deeper the red will be on maturity.
Behavior
Asian arowanas are paternal mouthbrooderMouthbrooder
Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a variety of different animals, most notably Darwin's...
s. They are slow to reach sexual maturity and difficult to breed in captivity; successful spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
s typically take place in large outdoor ponds rather than in aquaria
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...
.
Two breeders reported success using a garden pond measuring 18 feet (5.5 m) by 18 feet (5.5 m) by 3.5 feet (1.1 m) deep, with pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
maintained between 6.5 and 7.0. The fish were over five years old. The successful harvest took place after the third spawning; in the first two spawnings, the male swallowed the eggs, possibly due to improper water quality.
Conservation
The Asian arowanas are listed as endangeredEndangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
by the 2006 IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
, with the most recent evaluation taking place in 1996. International trade in these fishes is controlled under the Convention on the International Trade in Endangered Species of Wild Flora and Fauna
Convention on the International Trade in Endangered Species of Wild Flora and Fauna
CITES is a multilateral treaty, drafted as a result of a resolution adopted in 1963 at a meeting of members of the International Union for Conservation of Nature...
(CITES), under which it was placed on Appendix I, the most restrictive category, in 1975. S. formosus is one of only eight fish species listed on Appendix I. There are a number of registered CITES breeders in Asia and the specimens they produce can be imported into several nations. Other nations restrict or prohibit possession of Asian arowanas; for example, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
has listed this species under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
, and therefore it cannot be possessed in that country without a permit.
Declining habitat
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...
is a major threat. For example, Asian arowanas are now uncommon in the Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...
, where they were once widely distributed, due to environmental destruction. Inclusion in the IUCN Red List was originally based not on biological reasons but on practical ones: though widely distributed throughout southeast Asia, they have been harvested heavily by aquarium collectors. However, habitat loss is likely a greater threat than aquarium collecting.
There is no recent evaluation of conservation status
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
by IUCN. Additionally, considering the current confusion as to number of species as well as the wide distribution, conservation status needs to be reconsidered. All strains are probably endangered, but some (notably the super red and red-tailed golden) more critically than others.
The Asian arowana's high value as 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 has impacted its conservation
Conservation ethic
Conservation is an ethic of resource use, allocation, and protection. Its primary focus is upon maintaining the health of the natural world: its, fisheries, habitats, and biological diversity. Secondary focus is on materials conservation and energy conservation, which are seen as important to...
. Its popularity has soared since the late 1970s, and hobbyists may pay thousands of U.S. dollars
United States dollar
The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....
for one of these animals.
Beginning in 1989, CITES began allowing Asian arowanas to be traded, provided certain criteria were met, most notably that they were bred in captivity on a fish farm
Fish farming
Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...
for at least two generations. The first of these farms was in 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...
. Later, the Singapore government
Government of Singapore
The Government of Singapore is defined by the Constitution of the Republic of Singapore to mean the Executive branch of government, which is made up of the President and the Cabinet of Singapore. Although the President acts in his personal discretion in the exercise of certain functions as a check...
's Agri-food and Veterinary Authority (then called the Primary Production Department) and a local fish exporter collaborated in a captive breeding
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...
program. Asian arowanas legally certified by CITES for trade became available from this program in 1994.
Captive-bred arowanas that are legal for trade under CITES are documented in two ways. First, fish farms provide each buyer with a certificate of authenticity and a birth certificate. Second, each specimen receives an implanted microchip
Microchip implant (animal)
A microchip implant is an identifying integrated circuit placed under the skin of a dog, cat, horse, parrot or other animal. The chips are about the size of a large grain of rice and are based on a passive RFID technology....
, called a Passive Integrated Transponder (PIT), which identifies individual animals.
Genetic fingerprinting
Genetic fingerprinting
DNA profiling is a technique employed by forensic scientists to assist in the identification of individuals by their respective DNA profiles. DNA profiles are encrypted sets of numbers that reflect a person's DNA makeup, which can also be used as the person's identifier...
has been used to assess the genetic diversity
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....
of a captive population at a Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
fish farm in order to improve the management of this species. DNA markers that distinguish among different strains and between sexes have been identified, allowing aquaculturists to identify these characteristics in immature animals.
Care in captivity
Because they can grow up to 90 centimetres (35 inches) long, Asian arowanas require a large aquarium. They are territorialTerritory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
and may be kept with other Scleropages only in a very large aquarium, provided all fish are of similar size. Like other arowana
Arowana
Arowanas are freshwater bony fish of the family Osteoglossidae, also known as bonytongues. In this family of fishes, the head is bony and the elongate body is covered by large, heavy scales, with a mosaic pattern of canals. The dorsal and the anal fins have soft rays and are long based, while the...
s, they need a tight-fitting cover to prevent jumping. The water should be well-filtered, soft, and slightly acidic
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
, and maintained at a temperature of 24–30° C (75–86° F).
Asian arowanas are carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
and should be fed a high-quality diet of meaty food, such as shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
and cricket
Cricket (insect)
Crickets, family Gryllidae , are insects somewhat related to grasshoppers, and more closely related to katydids or bush crickets . They have somewhat flattened bodies and long antennae. There are about 900 species of crickets...
s. They are surface feeders and prefer to take food in the upper parts of the water column. Aquarists recommend live foods and meaty prepared foods. Examples of appropriate live foods include scorpions
Scorpion
Scorpions are predatory arthropod animals of the order Scorpiones within the class Arachnida. They have eight legs and are easily recognized by the pair of grasping claws and the narrow, segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger...
, centipedes
Chinese red-headed centipede
The Chinese red-headed centipede, also known as the Chinese red head, is a centipede from East Asia and Australasia. It averages 20 cm in length and lives in an aquatic environment....
, mealworm
Mealworm
Mealworms are the larval form of the mealworm beetle, Tenebrio molitor, a species of darkling beetle. Like all holometabolic insects, they go through four life stages: egg, larva, pupa, and adult...
s, cricket
Cricket (insect)
Crickets, family Gryllidae , are insects somewhat related to grasshoppers, and more closely related to katydids or bush crickets . They have somewhat flattened bodies and long antennae. There are about 900 species of crickets...
s, shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, feeder fish
Feeder fish
Feeder fish is the generic name for certain types of inexpensive fish commonly fed as live prey to captive animals such as sharks, turtles and some other fish such as oscars.-Advantages of using feeder fish:...
, small frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, and earthworm
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s. Prepared foods include prawns (shrimp), lean pork, frozen fish food, and pelleted food.