Gangetic whiting

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Gangetic whiting
Sillaginopsis panijus.png
Scientific classification
Kingdom:
Phylum:
Class:
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Genus:
Sillaginopsis

T. N. Gill, 1861
Species:
S. panijus
Binomial name
Sillaginopsis panijus
(Hamilton, 1822)
S.panujis distribution.png
Range of Gangetic whiting in dark blue
Synonyms

Sillago panijus Hamilton, 1822
Cheilodipterus panijus Hamilton, 1822
Sillaginopsis domina Cuvier, 1829
Sillago domina Cuvier, 1829

Contents

The Gangetic whiting, Sillaginopsis panijus (also known as the flathead sillago), is a species of inshore marine and estuarine fish of the smelt-whiting family, Sillaginidae. It is the most distinctive Asian member of the family due to its flattened head and trailing dorsal fins. Although first described in 1822, it was not placed in its own genus until 1861 when Theodore Gill erected Sillaginopsis, a genus which is still monotypic. Gangetic whiting are of minor commercial importance along the Southeast coast of the Asian continent where it inhabits protected areas.

Taxonomy and naming

The Gangetic whiting is the only species of the genus Sillaginopsis, which itself is one of three genera the family Sillaginidae, containing all the smelt whitings. The Sillaginidae are part of the Percoidei, a suborder of the order Perciformes. [1]

The Gangetic whiting was originally named Cheilodipterus panijus in 1822 by Francis Buchanan-Hamilton from a holotype taken from the Ganges estuary in India. The species was further examined by Gill in 1861 in the first review of the family, entitled "Synopsis of the Sillaginoids", which led to the creation of the genus Sillaginopsis. This new classification changed the binomial name to the currently accepted Sillaginopsis panijus. [2]

Description

The distinct appearance of the Gangetic whiting makes it the easiest of the smelt whitings to identify. The head of the species is highly depressed, like that of the flatheads, with very small eyes well constricted by the orbits. [3] The first dorsal fin contains ten spines including a large trailing second spine; the second dorsal fin has one spine and 25 to 27 soft rays. The anal fin has two spines and 24 to 27 soft rays. There are 84 to 90 lateral line scales and the species has a total of 42 vertebrae. The species is known to grow to a length of 44 cm. [4]

Another unique feature of this species is its severe reduction or even absence of a swim bladder, which all other members of the family Sillaginidae possess. The Gangetic whiting also has a small mouth with a much shorter lower jaw than upper jaw, with the two anteriormost teeth larger than the rest. [2]

Distribution and habitat

The Gangetic whiting is found on the southern Asian coast from Puducherry in the east, northward along the Coromandel Coast and the Ganges delta, Myanmar, Malaysia and occasionally as far south as the Indonesian archipelago. [2]

The species is often found on silty or muddy substrates in shallow, open bays and estuaries along the coast. Juveniles usually migrate into the upper reaches of estuaries for protection against predation by larger species. [3]

Biology

Gut content analysis has found the Gangetic whiting consumes numerous small fish, benthic and planktonic crustaceans and algae, with its small mouth size restricting the size of food portions. [4]

The Gangetic whiting is the only known species of fish to host the intestinal parasite Dichelyne alatae , found in specimens in West Bengal, [5] with a number of other parasites identified from it.

Otolith and size-age composition studies by Krishnayya (1963) of the commercial catches from the Hooghly River estuary and found that S. panijus probably spawns twice a year during the periods of November to February and August to September. The juveniles migrate toward the upper reaches during March and April and during December where they remain for two to three months. Sexual maturity is attained at a length of about 120 mm. [6]

Relationship to humans

A local fishery exists along the coast of the Bay of Bengal primarily near or on the river deltas, with commercially important fish captured by nets and longlines in the Hooghly and Ganges delta. The Gangetic whiting is sold fresh in local markets, rarely making its way to overseas markets. [2] Juvenile Sillaginopsis panijus are also occasionally traded as brackish water aquarium fish. [7]

Related Research Articles

Sillaginidae

The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family of benthic coastal marine fish in the order Perciformes. The smelt-whitings inhabit a wide region covering much of the Indo-Pacific, from the west coast of Africa east to Japan and south to Australia. The family comprises only five genera and 35 species, of which a number are dubious, with the last major revision of the family in 1992 unable to confirm the validity of a number of species. They are elongated, slightly compressed fish, often light brown to silver in colour, with a variety of markings and patterns on their upper bodies. The Sillaginidae are not related to a number of fishes commonly called 'whiting' in the Northern Hemisphere, including the fish originally called whiting, Merlangius merlangus.

Oriental trumpeter whiting

The oriental trumpeter whiting, Sillago aeolus, is a widely distributed species of benthic inshore fish in the smelt-whiting family. The species ranges from east Africa to Japan, inhabiting much if the southern Asian and Indonesian coastlines. Its morphology is very similar to other species within the genus Sillago, with a long, compressed body and silvery overall colour. It can be distinguished from its relatives by colour patterns and particularly swim bladder morphology, which helps define most species of Sillago. S aeolus is a benthic predator, consuming a variety of crustaceans and polychaetes. As with most members of the smelt whiting family, it is important to small coastal fisheries in various areas of its range.

Shortnose whiting

The shortnose whiting, Sillago arabica, is a recently described and poorly known species of inshore marine fish of the smelt whiting family Sillaginidae that inhabits only the Persian Gulf. S. arabica is similar in morphology to other sillaginids, although has a distinctive shortened snout which gives the species its common name. This species is of no current interest to local fisheries, although beach seines may take minor amounts of this species.

Asian whiting

The Asian whiting, Sillago asiatica, is a species inshore marine fish in the smelt whiting family, Sillaginidae, distributed along the Asian coastline from the Gulf of Thailand to Taiwan. The Asian whiting's appearance is very similar to other closely related species in the genus Sillago, with swim bladder morphology and ray counts of fins the most reliable identifying features. The species inhabits slightly deeper water than many of the sillaginid species its distribution overlaps, forming an important part of the whiting fishery in the countries within its range.

Slender whiting

The slender whiting is a poorly known species of inshore marine fish of the smelt whiting family, Sillaginidae that has a distribution limited to the Persian Gulf only. The Slender whiting, like most sillaginids requires careful study to determine its identity, with ray and vertebrae counts as well as swim bladder morphology distinguishing features. This inshore species of fish is commonly taken by fishermen using beach seines and is sold fresh in local markets.

Western trumpeter whiting

The western trumpeter whiting, Sillago burrus, is a species of marine fish of the smelt whiting family Sillaginidae that is commonly found along the northern coast of Australia and in southern Indonesia and New Guinea. As its name suggests, it is closely related to and resembles the trumpeter whiting which inhabits the east coast of Australia and is distinguishable by swim bladder morphology alone. The species inhabits a variety of sandy, silty and muddy substrates in depths from 0 to 15 m deep, with older fish inhabiting deeper waters. Western trumpeter whiting are benthic carnivores which take predominantly crustaceans and polychaetes as prey. The species reaches sexual maturity at the end of its first year of age, spawning in batches between December and February The species is taken as bycatch with other species of whiting and shrimps in Australia.

Sand whiting

The sand whiting, also known as the summer whiting, yellowfin whiting or blue-nose whiting, is a common species of coastal marine fish of the family Sillaginidae, the smelt-whitings. It is a slender, slightly compressed fish that is very similar to other species of Sillago, with detailed spine, ray and lateral line scale counts needed to distinguish the species between its nearest relative Sillago analis. The sand whiting is distributed along the east coast of Australia from Cape York south to Tasmania, as well as Lord Howe Island and New Caledonia in the Pacific Ocean.

Indian whiting

The Indian whiting is a poorly known species of coastal marine fish of the smelt-whiting family Sillaginidae. The species was named in 1985, having previously being misidentified as another species of Sillago, S. parvisquamis. The Indian whiting inhabits the east and west coasts of the Indian subcontinent, apparently not extending to the southern tip of India. Like all sillaginids, it is benthic in nature, living in depths to 30 m where it is caught by fishermen alongside other species of Sillago.

Thai whiting

The Thai whiting, Sillago intermedius, is a species of coastal marine fish of the smelt-whiting family Sillaginidae. The Thai whiting ranges from the west coast of India to the Gulf of Thailand in the east, inhabiting silty substrates in shallow waters. First identified in 1977 from a specimen found in a fish market, the species has had little research performed on its biology, and is frequently misidentified as Sillago sihama or Sillago maculata Thai whiting are commonly caught by fishermen throughout their range and are marketed fresh locally.

Japanese whiting

The Japanese whiting, Sillago japonica, is a common species of coastal marine fish belonging to the smelt-whiting family, Sillaginidae. As suggested by its name, the Japanese whiting was first recorded from Japan in 1843, but has subsequently been found to extend to Korea, China and Taiwan.

Mud whiting

The mud whiting, Sillago lutea, is a species of coastal marine fish in the smelt-whiting family Sillaginidae. The mud whiting was first described in 1985 and is currently known from the north west coast of Australia and the Indian coast.

Large-scale whiting

The large-scale whiting the only member of the genus Sillaginops, is a poorly understood species of coastal marine fish of the smelt- whiting family Sillaginidae. First described in 1859, the large-scale whiting is known to inhabit shallow waters along the coasts of a number of Indo-Pacific countries including Japan, Indonesia, Philippines and the Solomon Islands. Little is known of the species biology, even though it is of minor importance to fisheries throughout its range.

Trumpeter whiting

The trumpeter whiting, Sillago maculata, is a common species of coastal marine fish of the smelt-whiting family, Sillaginidae. The trumpeter whiting is endemic to Australia, inhabiting the eastern seaboard from southern New South Wales to northern Queensland. The species is found in bays, estuaries, coastal lakes and mangrove creeks on silty and muddy substrates in waters ranging from 0 to 30 m deep, occasionally inhabiting sandy and seagrass beds.

Large-headed whiting

The large-headed whiting, Sillago megacephalus, is a dubious species of coastal marine fish in the smelt-whiting family that has only been recorded from one specimen captured off the coast of China in 1933. Although very similar to Sillago sihama, the species is characterised by an unusually large head which accounts for 33% of the total body length.

Small-eyed whiting

The small-eyed whiting, Sillago microps, is a poorly known species of coastal marine fish of the smelt-whiting family Sillaginidae. The species is known from only two specimens; the holotype collected by Roland McKay in 1985 from a Taipei market, both specimens of which were taken from the waters of Taiwan. Apart from a relatively small eye size, the species is hard to distinguish from other common species of sillaginid taken in the area, and may be a minor part of local fisheries.

Northern whiting

The northern whiting, Sillago sihama, is a marine fish, the most widespread and abundant member of the smelt-whiting family Sillaginidae. The northern whiting was the first species of sillaginid scientifically described and is therefore the type species of both the family Sillaginidae and the genus Sillago. The species is distributed in the Indo-Pacific region from South Africa in the west to Japan and Indonesia in the east, also becoming an invasive species to the Mediterranean through the Suez Canal. The northern whiting inhabits coastal areas to 60 m, but is most often found in shallow water around bays and estuaries, often entering freshwater. It is a carnivore, taking a variety of polychaetes and crustaceans. The species is of major economic importance throughout the Indo-Pacific. It is most frequently taken by seine nets and cast nets and marketed fresh.

Small-scale whiting

The small-scale whiting, is a species of inshore marine fish of the smelt-whiting family Sillaginidae. The small-scale whiting is very similar in body shape and colour to other species in the genus Sillago, but is distinguished by having 12 or 13 spines in the first dorsal fin compared to 11 in all other species. The species is distributed through parts of the west Pacific Ocean including Japan, Taiwan, Korea and India, inhabiting the tidal flats of major estuaries. It is a benthic predator taking crustaceans, molluscs and annelids. Spawning in the species takes place from May to September, with peaks identified in June and July. The eggs and larvae have been extensively studied in order to distinguish them from the more abundant Sillago sihama. Minor fisheries exist for the small-scale whiting, although it is thought be endangered by habitat loss and pollutionIUCN.

Soringa whiting

The Soringa whiting, Sillago soringa, is a poorly known species of coastal marine fish of the smelt-whiting family, Sillaginidae. The Soringa whiting is known exclusively from the east coast of India, inhabiting shallow inshore environments, particularly sandy substrates. S. soringa was first described in 1982 by Dutt and Sujatha, with the taxonomic status of the species was questioned by Roland McKay in his review of the Sillaginidae, with similar features to S. asiatica suggesting it is a senior synonym of the latter.

Estuarine whiting

The estuarine whiting, Sillago vincenti, is a species of benthic inshore marine fish of the smelt-whiting family, Sillaginidae. The estuarine whiting is very similar in appearance to the northern whiting, Sillago sihama, and as such was mistaken for the latter until 1980, when R.J. McKay identified the species based primarily on swimbladder morphology. The estuarine whiting is distributed along both the east and west coasts of India, primarily inhabiting the muddy substrates of estuaries. The species is locally important to fisheries in India, and is recognized as having aquaculture potential.

Chinese sillago

The Chinese sillago is a species of recently described inshore marine fish in the smelt whiting family Sillaginidae. The species is known only to inhabit the coastal waters of China, primarily in estuarine tidal flats. The Chinese sillago was described in 2011 based on morphological and DNA barcode analysis of several specimens. Several detailed anatomic features distinguish it from other sillaginids, with Sillago parvisquamis its closest relative based on phylogenetic analysis. Nothing is known of the ecology or importance to fisheries of the Chinese sillago.

References

  1. "Sillaginopsis panijus". Integrated Taxonomic Information System . Retrieved 5 May 2008.
  2. 1 2 3 4 McKay, R.J. (1992). FAO Species Catalogue: Vol. 14. Sillaginid Fishes Of The World (PDF). Rome: Food and Agricultural Organisation. pp. 19–20. ISBN   92-5-103123-1.[ permanent dead link ]
  3. 1 2 McKay, R.J. (1985). "A Revision of the Fishes of the Family Sillaginidae". Memoirs of the Queensland Museum. 22 (1): 1–73.
  4. 1 2 Froese, Rainer and Pauly, Daniel, eds. (2014). "Sillaginopsis panijus" in FishBase . November 2014 version.
  5. De, N.C.; Maity, R.N. (1995). "A new nematode, Dichelyne alatae sp. n. (Cucullanidae), from Sillaginopsis panijus (Pisces) of West Bengal, India". Folia Parasitologica. 42 (3): 220–226.
  6. Krishnayya, C.G. (1963). "On the use of otoliths in the determination of age and growth of the Gangetic whiting, Sillago panijus (Ham.Buch.), with notes on its fishery in Hooghly estuary". Indian Journal of Fisheries. 10: 391–412.
  7. Schaefer, F. (2005). Brackish-water fishes : all about species, care and breeding. Rodgau: Aqualog. ISBN   3-936027-82-X.