''Trachidermus fasciatus'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of fish in the superfamily

Cottoidea A sculpin is a type of fish that belongs to the superfamily Cottoidea in the order Perciformes.Kane, E. A. and T. E. Higham. (2012)Life in the flow lane: differences in pectoral fin morphology suggest transitions in station-holding demand acros ...

, the sculpins, and the only member of the

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

''Trachidermus''. Its common name is roughskin sculpin. It has also been called four-gilled perch. It is native to the coastlines of

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, and

Korea Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically Division of Korea, divided at or near the 38th parallel north, 3 ...

, where it occurs at the mouths of rivers.

Description

This species is up to about long and weighs up to . It has a large, spineless head with a wide mouth and small eyes near the tip of the snout. The upper jaw is slightly projecting. The dorsal fin has 8 spines and 19 to 20 soft rays and the anal fin has no spines but 17 to 18 soft rays. This fish lacks

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 ...

but its body surface is textured with knobbles. The gill opening is large and each

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

has two orange stripes. This fish lives in rivers,

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 environm ...

, and coastal ocean waters. It is

catadromous Fish migration is animal migration, mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few ...

; adults

spawn Spawn or spawning may refer to: * Spawning, 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: Armageddon' ...

mudflat Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...

s at the river mouths, and after hatching, the juveniles swim upstream to

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

river habitat.

Breeding

The female often lays eggs in empty

bivalve shell A bivalve shell is the enveloping exoskeleton or mollusc shell, shell of a bivalve mollusc, composed of two hinged halves or ''valve (mollusc), valves''. The two half-shells, called the "right valve" and "left valve", are joined by a ligament and ...

s. Nests have been noted in the shells of the

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but no ...

Crassostrea rivularis ''Crassostrea'' is a genus of true oysters (family Ostreidae) containing some of the most important oysters used for food. The genus was recent split in WoRMS, following the DNA-based phylogenies of Salvi ''et al.'' (2014 and 2017). Pacific spec ...

'' and the

clam Clam is a common name for several kinds of bivalve mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...

Atrina pectinata ''Atrina pectinata'' is a species of bivalves belonging to the family Pinnidae. The species is found in the Old World. They are important in commercial fishing in Asia. They have the common name of ''kijogae'' 'pen shells'' ''A. pectinata'' is ...

''. It will also use other readily available structures for nesting, such as concrete blocks, lengths of

bamboo Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...

, or

glass bottle Common uses for bottles made from glass include food condiments, soda, liquor, cosmetics, pickling and preservatives; they are occasionally also notably used for the informal distribution of notes. A glass bottle can vary in size considerably, b ...

s. The male often guards the nest. The eggs are reddish-yellow to

tangerine The tangerine is a type of citrus fruit that is orange in colour, that is considered either a variety of the mandarin orange (''Citrus reticulata''), or a closely related species, under the name ''Citrus tangerina'', or yet as a hybrid (''Citr ...

in color, about in width, and sticky in texture, adhering to the shell or other nest material. The larval fish is about long at hatching.

Feeding

This species is a bottom-dwelling fish and is a

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

. The adult feeds on small fish and

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

s. The juveniles feed on

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

, such as

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

s. In the

Ariake Sea The is a body of salt water surrounded by Fukuoka, Saga, Nagasaki, and Kumamoto Prefectures, all of which lie on the island of Kyūshū in Japan. It is the largest bay in Kyūshū. Its deepest point is only about 50 meters (165 ft) deep, and ext ...

of Japan the juveniles show a clear preference for the

calanoid Calanoida is an order of copepods, a group of arthropods commonly found as zooplankton. The order includes around 46 families with about 1800 species of both marine and freshwater copepods between them. Description Calanoids can be distinguish ...

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

species '' Sinocalanus sinensis''. Juveniles have been reared in the laboratory on diets of midge larvae, water fleas, and the

brine shrimp ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp or ''Sea-Monkeys, sea monkeys''. It is the only genus in the Family (biology), family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to t ...

Artemia salina ''Artemia salina'' is a species of brine shrimp – aquatic crustaceans that are more closely related to '' Triops'' and cladocerans than to true shrimp. It belongs to a lineage that does not appear to have changed much in . ''Artemia salina'' i ...

''.

Status

The habitat of the fish is degraded in some areas, particularly the river mouths of coastal China.

Pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

from rapid urban development,

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

, and the construction of

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

s and

dikes Dyke or dike may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), formations of magma or sediment that cut through and across the layering of adjacent rocks * Dike (mythology), ''Dikē'', the Greek goddess ...

threaten the species in this region. Changes in the hydrology of the area, mainly from dams, are most concerning because they prevent the migration of the fish in the river systems.

References

{{Taxonbar, from=Q1852775 Cottinae Fish described in 1837 Fish of Asia Taxa named by Johann Jakob Heckel