Indian threadfish
Encyclopedia
The Indian threadfish, Alectis indicus, (also known as the Indian threadfin, diamond trevally, mirror fish and plumed trevally) is a large species
of coastal marine
fish
of the jack family, Carangidae
. The species is widespread in the waters of the tropical Indo-West Pacific Ocean
, ranging from east Africa
to India
, Asia
, Indonesia
and Australia
. Adult fish tend to inhabit coastal waters over reefs down to 100 m in depth, while juveniles inhabit a variety of environments including estuaries and seagrass beds. The Indian threadfish is similar to the other two species in the genus Alectis
, with a slight concavity in the profile of the head the most obvious distinguishing feature. It is a large species, growing to 165 cm and 25 kg in weight. The species is carnivorous, consuming fishes, cephalopod
s and crustacean
s.
The Indian threadfin is of minor commercial importance, and has been the subject of aquaculture
in Singapore
.
Alectis
, which itself is one of 33 genera encapsulated in the jack family
, Carangidae
. The Carangidae are perciform fishes in the suborder Percoidei
.
The species was first recognized and scientifically described by the German naturalist
Eduard Rüppell
in 1830 under the name Scyris indicus, with the type specimen collected from the Red Sea
. After Rüppell's designation, a number of other naturalists unknowingly re-described the species, with the names Hynnis insanus, Caranx gallus and Hynnis momsa applied to the species by the various authors. Rüppell's original classification was also revised; the fish was first placed in Seriolichthys, and finally in the senior genus Alectis by Ogilby
in 1913. The species' name has occasionally been misspelled as Alectis indica in the literature
. All names except A. indicus are considered invalid under the ICZN
naming rules and have been discarded.
The common name
of the species, 'Indian threadfish' or 'Indian threadfin' refers to its distribution which includes India
n waters, and the characteristic elongated dorsal fins in juveniles
. Other common names, such as mirror fish and diamond trevally, describe other aspects of the species' appearance.
structure of a large jack, with a distinctly angular, strongly compressed body. The major identifying feature of the species is its head profile, having a slight concavity near the eye
s which distinguishes it from its close relatives in the genus Alectis. The dorsal profile of the fish is more curved than the ventral profile, and the body is deepest between the origins of the soft dorsal
and soft anal fins. The first section of the dorsal fin consists of 5 to 7 visible spines, with the second section having one spine and 18 or 19 soft rays. The anal fin has two spines followed by a single spine and 15 or 16 soft rays. The pectoral fin is long and curved, extending beyond the junction of the straight and curved sections of the lateral line
. The body appears to be scaleless, but on closer inspection has minute, deeply embedded scales
. The lateral line is strongly curved anteriorly, with a section of 6 to 11 scute
s toward the tail. Juveniles have long, filamentous trailing anal and dorsal fin spines, much like those of Alectis ciliaris. The species is known to grow to 165 cm and 25 kg.
The body of adults is a silvery blue-green colour above, being darkest on the head and silver below. The upper operculum
has a small diffuse dark spot. The long filamentous soft dorsal and anal fins as well as the pelvic fin are a dark blue to black colour, while the others are pale green to hyaline
in appearance. Juveniles have 5 to 7 broad dark vertical cross bands through their body.
and Western Pacific Oceans, ranging from Madagascar
, east Africa
and the Red Sea
to India, China
, South East Asia, north to Japan
and south to Indonesia
and northern Australia
. The eastern most report is that of a specimen taken off French Polynesia
in the Pacific.
The species is generally an inhabitant of coastal waters from depths of 20 m to 100 m, although the juveniles may be pelagic, riding ocean current
s. In some years currents bring the juveniles as far south as Sydney, Australia where they inhabit of estuaries in the summer, before dying off in the cold winter. The African pompano
shows a similar pattern in Australian waters. The juveniles are also known to inhabit estuaries in other regions (including South Africa) as well as seagrass beds. Adults generally inhabit areas of reef
below 20 m.
s, jellyfish
and crustacean
s. As with A. ciliaris, the trailing fins of juveniles are thought to resemble jellyfish medusa
e, causing predators to avoid the young fish. Relatively little is known about reproduction in the species, although observations made in Indonesia show spawning
occurs in pairs at daytime between ebbing and flooding tide
s. The spawning area in this instance was a shoal
of 35–45 m, located in a deeper channel between two islands.
of minor importance throughout its range, often forming part of artisanal fishery catches. Beach seines and hook-and-line methods are the predominant methods of capture. Archaeological evidence has shown that the species has long been a resource for humans, with prehistoric and more modern sites in the United Arab Emirates
yielding the preserved remains of this species, as well as a number of other carangids.
The species is commercially farmed in small numbers in Singapore
using aquaculture
techniques. These farmed fish generally sell for between 7 and 11 US dollars per kg, as high or higher than other jacks farmed in the country. They are also considered quality gamefish, although are not purposely targeted by anglers, and are often taken as bycatch.
Juveniles are moderately popular aquarium
fishes, but require fairly large tanks and peaceful neighbours.
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 coastal marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
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...
of the jack family, Carangidae
Carangidae
Carangidae is a family of fish which includes the jacks, pompanos, jack mackerels, and scads.They are marine fish found in the Atlantic, Indian and Pacific Oceans...
. The species is widespread in the waters of the tropical Indo-West Pacific Ocean
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
, ranging from east Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
to India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, 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 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...
. Adult fish tend to inhabit coastal waters over reefs down to 100 m in depth, while juveniles inhabit a variety of environments including estuaries and seagrass beds. The Indian threadfish is similar to the other two species in the genus Alectis
Alectis
Alectis is a genus of fish in the family Carangidae containing three extant species, all of which are large marine fishes. They are commonly known as threadfish, diamond trevallies and occasionally pompanos, although they have no close affiliation with the true pompano genus.-Taxonomy:Alectis is...
, with a slight concavity in the profile of the head the most obvious distinguishing feature. It is a large species, growing to 165 cm and 25 kg in weight. The species is carnivorous, consuming fishes, cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s.
The Indian threadfin is of minor commercial importance, and has been the subject of aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
in 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...
.
Taxonomy and naming
The Indian threadfish is one of three members of the diamond trevally genusGenus
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...
Alectis
Alectis
Alectis is a genus of fish in the family Carangidae containing three extant species, all of which are large marine fishes. They are commonly known as threadfish, diamond trevallies and occasionally pompanos, although they have no close affiliation with the true pompano genus.-Taxonomy:Alectis is...
, which itself is one of 33 genera encapsulated in the jack 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...
, Carangidae
Carangidae
Carangidae is a family of fish which includes the jacks, pompanos, jack mackerels, and scads.They are marine fish found in the Atlantic, Indian and Pacific Oceans...
. The Carangidae are perciform fishes in the suborder Percoidei
Percoidei
Percoidei is one of eighteen suborders of bony fish in the order Perciformes. Many commercially harvested fish species are contained in this suborder, including the snappers, jacks, whitings, groupers, bass, perches and porgies.-Divisions:...
.
The species was first recognized and scientifically described by the German naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
Eduard Rüppell
Eduard Rüppell
Wilhelm Peter Eduard Simon Rüppell was a German naturalist and explorer. Rüppell is occasionally transliterated to "Rueppell" for the English alphabet....
in 1830 under the name Scyris indicus, with the type specimen collected from the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
. After Rüppell's designation, a number of other naturalists unknowingly re-described the species, with the names Hynnis insanus, Caranx gallus and Hynnis momsa applied to the species by the various authors. Rüppell's original classification was also revised; the fish was first placed in Seriolichthys, and finally in the senior genus Alectis by Ogilby
Ogilby
Ogilby may refer to:*John Ogilby, a Scottish translator, impresario and cartographer*William Ogilby, an Irish barrister and naturalist*James Douglas Ogilby , an Australian zoologist, son of William Ogilby...
in 1913. The species' name has occasionally been misspelled as Alectis indica in the literature
Literature
Literature is the art of written works, and is not bound to published sources...
. All names except A. indicus are considered invalid under the ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
naming rules and have been discarded.
The common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
of the species, 'Indian threadfish' or 'Indian threadfin' refers to its distribution which includes India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n waters, and the characteristic elongated dorsal fins in juveniles
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
. Other common names, such as mirror fish and diamond trevally, describe other aspects of the species' appearance.
Description
The Indian threadfish has the typical bodyBody
With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...
structure of a large jack, with a distinctly angular, strongly compressed body. The major identifying feature of the species is its head profile, having a slight concavity near the eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s which distinguishes it from its close relatives in the genus Alectis. The dorsal profile of the fish is more curved than the ventral profile, and the body is deepest between the origins of the soft 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 soft anal fins. The first section of the dorsal fin consists of 5 to 7 visible spines, with the second section having one spine and 18 or 19 soft rays. The anal fin has two spines followed by a single spine and 15 or 16 soft rays. The pectoral fin is long and curved, extending beyond the junction of the straight and curved sections of the 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...
. The body appears to be scaleless, but on closer inspection has minute, deeply embedded scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
. The lateral line is strongly curved anteriorly, with a section of 6 to 11 scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s toward the tail. Juveniles have long, filamentous trailing anal and dorsal fin spines, much like those of Alectis ciliaris. The species is known to grow to 165 cm and 25 kg.
The body of adults is a silvery blue-green colour above, being darkest on the head and silver below. The upper operculum
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....
has a small diffuse dark spot. The long filamentous soft dorsal and anal fins as well as the pelvic fin are a dark blue to black colour, while the others are pale green to hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
in appearance. Juveniles have 5 to 7 broad dark vertical cross bands through their body.
Distribution and habitat
The Indian threadfish inhabits the tropical regions of the IndianIndian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
and Western Pacific Oceans, ranging from Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, east Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
and the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
to India, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, South East Asia, north to Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and south to 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 northern 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...
. The eastern most report is that of a specimen taken off French Polynesia
French Polynesia
French Polynesia is an overseas country of the French Republic . It is made up of several groups of Polynesian islands, the most famous island being Tahiti in the Society Islands group, which is also the most populous island and the seat of the capital of the territory...
in the Pacific.
The species is generally an inhabitant of coastal waters from depths of 20 m to 100 m, although the juveniles may be pelagic, riding ocean current
Ocean current
An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun...
s. In some years currents bring the juveniles as far south as Sydney, Australia where they inhabit of estuaries in the summer, before dying off in the cold winter. The African pompano
African pompano
The African pompano, Alectis ciliaris, is a widely distributed species of tropical marine fish in the Jack family, Carangidae. The species is found in tropical waters worldwide, with adults often inhabiting coastlines while juveniles are usually pelagic, floating with ocean currents...
shows a similar pattern in Australian waters. The juveniles are also known to inhabit estuaries in other regions (including South Africa) as well as seagrass beds. Adults generally inhabit areas of reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
below 20 m.
Biology
The Indian threadfish is a predatory fish, consuming of a wide range of fishes, small squidSquid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
s, jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s. As with A. ciliaris, the trailing fins of juveniles are thought to resemble jellyfish medusa
Medusa
In Greek mythology Medusa , " guardian, protectress") was a Gorgon, a chthonic monster, and a daughter of Phorcys and Ceto. The author Hyginus, interposes a generation and gives Medusa another chthonic pair as parents. Gazing directly upon her would turn onlookers to stone...
e, causing predators to avoid the young fish. Relatively little is known about reproduction in the species, although observations made in Indonesia show 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...
occurs in pairs at daytime between ebbing and flooding tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
s. The spawning area in this instance was a shoal
Shoal
Shoal, shoals or shoaling may mean:* Shoal, a sandbank or reef creating shallow water, especially where it forms a hazard to shipping* Shoal draught , of a boat with shallow draught which can pass over some shoals: see Draft...
of 35–45 m, located in a deeper channel between two islands.
Relationship to humans
The Indian threadfish is a commercial fishFishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
of minor importance throughout its range, often forming part of artisanal fishery catches. Beach seines and hook-and-line methods are the predominant methods of capture. Archaeological evidence has shown that the species has long been a resource for humans, with prehistoric and more modern sites in the United Arab Emirates
United Arab Emirates
The United Arab Emirates, abbreviated as the UAE, or shortened to "the Emirates", is a state situated in the southeast of the Arabian Peninsula in Western Asia on the Persian Gulf, bordering Oman, and Saudi Arabia, and sharing sea borders with Iraq, Kuwait, Bahrain, Qatar, and Iran.The UAE is a...
yielding the preserved remains of this species, as well as a number of other carangids.
The species is commercially farmed in small numbers in 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...
using aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
techniques. These farmed fish generally sell for between 7 and 11 US dollars per kg, as high or higher than other jacks farmed in the country. They are also considered quality gamefish, although are not purposely targeted by anglers, and are often taken as bycatch.
Juveniles are moderately 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...
fishes, but require fairly large tanks and peaceful neighbours.