The Gangetic whiting, ''Sillaginopsis panijus'' (also known as the flathead sillago), is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of inshore marine and

estuarine fish Coastal fish, also called inshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf. Since the continental shelf is usually less than deep, it follows that pelagic coastal fish are generally ep ...

of the smelt-whiting family, Sillaginidae. It is the most distinctive

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

n member of the family due to its flattened head and trailing

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

s. Although first described in 1822, it was not placed in its own genus until 1861 when

Theodore Gill Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural histo ...

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 Percoidei is one of 3 suborders of bony fishes in the order Perciformes. Many commercially harvested fish species are considered to be contained in this suborder, including the snappers, groupers, basses, goatfishes and perches. Divisions The ...

, a suborder of the order

Perciformes Perciformes (), also called the Percomorpha or Acanthopteri, is an order or superorder of ray-finned fish. If considered a single order, they are the most numerous order of vertebrates, containing about 41% of all bony fish. Perciformes means ...

. The Gangetic whiting was originally named ''Cheilodipterus panijus'' in 1822 by Francis Buchanan-Hamilton from a

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

taken from the

Ganges The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. 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''.

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 In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

. The first

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 Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...

and the species has a total of 42

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

e. The species is known to grow to a length of 44 cm. 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 The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

than upper jaw, with the two anteriormost teeth larger than the rest.

Distribution and habitat

The Gangetic whiting is found on the southern Asian coast from

Puducherry Puducherry or Pondicherry may refer to: * Puducherry (union territory), a union territory of India ** Pondicherry, capital of the union territory of Puducherry ** Puducherry district, a district of the union territory of Puducherry ** Puducherry t ...

in the east, northward along the

Coromandel Coast The Coromandel Coast is the southeastern coastal region of the Indian subcontinent, bounded by the Utkal Plains to the north, the Bay of Bengal to the east, the Kaveri delta to the south, and the Eastern Ghats to the west, extending over an ...

and the Ganges delta,

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

and occasionally as far south as the

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arc ...

. The species is often found on

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...

y or muddy substrates in shallow, open bays and

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

along the coast. Juveniles usually migrate into the upper reaches of estuaries for protection against

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

by larger species.

Biology

Gut content analysis has found the Gangetic whiting consumes numerous small fish, benthic and

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s and algae, with its small mouth size restricting the size of food portions. The Gangetic whiting is the only known species of fish to host the

intestinal parasite An intestinal parasite infection is a condition in which a parasite infects the gastro-intestinal tract of humans and other animals. Such parasites can live anywhere in the body, but most prefer the intestinal wall. Routes of exposure and inf ...

'' Dichelyne alatae'', found in specimens in

West Bengal West Bengal (, Bengali: ''Poshchim Bongo'', , abbr. WB) is a state in the eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabitants within an area of . West Bengal is the fou ...

, with a number of other parasites identified from it.

Otolith An otolith ( grc-gre, ὠτο-, ' ear + , ', a stone), also called statoconium or otoconium or statolith, is a calcium carbonate structure in the saccule or utricle of the inner ear, specifically in the vestibular system of vertebrates. The sa ...

and size-age composition studies by Krishnayya (1963) of the commercial catches from the Hooghly River estuary and found that ''S. panijus'' probably

spawn Spawn or spawning may refer to: * Spawn (biology), the eggs and sperm of aquatic animals Arts, entertainment, and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** '' Spawn: ...

s 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 Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definit ...

is attained at a length of about 120 mm.

Relationship to humans

A local fishery exists along the coast of the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line betwee ...

primarily near or on the

river delta A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more ra ...

s, 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. Juvenile ''Sillaginopsis panijus'' are also occasionally traded as

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

aquarium fish.

References

{{Taxonbar, from=Q3229859 Sillaginidae Fish of South Asia Fish described in 1822