 = Stephanolepis cirrhifer = 
 
 Stephanolepis cirrhifer , commonly known as the thread @-@ sail filefish , is a species of marine fish in the family Monacanthidae . It is found in the western Pacific , in an area that ranges from northern Japan to the East China Sea , to Korea . Other common names for the fish include " Kawahagi " ( Japanese ) and " Jwi @-@ chi " ( Korean ) . The fish grows to a maximum length of about 12 inches ( 30 centimetres ) , and consumes both plant material and small marine organisms like skeleton shrimp . S. cirrhifer is host of the parasite Peniculus minuticaudae . Some minor genetic differentiation between S. cirrhifer born in the wild and those bred in a hatchery for consumer use has been shown . The fish is edible and sold commercially for culinary purposes in many Asian countries . 
 
 = = Taxonomy = = 
 
 The fish was first described in 1850 by Coenraad Jacob Temminck and Hermann Schlegel , when it was observed along with other fauna off the coasts of Japan . They initially placed it in the genus Monacanthus , as Monacanthus cirrhifer ; however , it was transferred to the genus Stephanolepis by David Starr Jordan and Henry Weed Fowler in 1903 . The species name derives from the Latin word cirrhifer , which means " bearing fringes of hair " . 
 Other common names : 
 Japanese - Kawahagi 
 Korean - Jwi @-@ chi 
 English - File fish , Fool fish , Porky 
 Russian - Small striped triggerfish ( Спинорог малый полосатый ) 
 
 = = Description and habitat = = 
 
 Thread @-@ sail filefish grow to a maximum adult length of about 30 centimetres ( 12 inches ) . The first dorsal fin is a strong retractable ( folding backwards ) spine . The second dorsal fin and anal fin are soft . They have comparatively small pectoral fins and truncated , fan @-@ shaped tail fins . The dorsal and anal fins are colorless . Their second dorsal , anal and caudal fins rounded . In males , 1 @-@ 3 soft dorsal fin rays extended as filaments ; the first ray has a particularly long thread . The fish have a small abdominal spike . The fish are colored from light brown , to grayish- to light greenish @-@ beige , and are slightly patterned with irregular , broken stripes that range from medium brown to blackish . 
 Juveniles of the species usually seek shelter and safety from predators within clusters of drifting seaweed . The adult thread @-@ sail filefish usually reside near the seabed , where the depth is around 10 metres ( 33 feet ) . The fish migrate wholly in ocean waters ( " oceanodromous " ) between their feeding and spawning grounds , which can cover a range of over 100 kilometres ( 62 miles ) . The spawning season lasts from May to August . Juveniles under 5 centimetres ( 2 @.@ 0 inches ) inhabit shallow water and feed on small crustaceans , mollusks and algae . Adult fish are mostly solitary and live among the coral and seaweeds . 
 
 = = Ecology = = 
 
 The thread @-@ sail filefish is an omnivore , and can feed on plant or animal matter . Its diet includes kelp , but consists mainly of amphipods such as gammarids and skeleton shrimp , as well as the seagrass species Zostera marina . The fish also feeds upon smaller organisms , including bryozoans and some species of serpulid tube worms . 
 Thread @-@ sail filefish feed on fish , amphipods , isopods , cirripeds , polychaetes , pelecypods , seaweeds such as those of the genus Sargassum ; and gelatinous plankton , such as the moon jellyfish Aurelia sp. and the giant jellyfish Nemopilema nomurai . 
 S. cirrhifer is host of the pennellid copepod parasite Peniculus minuticaudae , which mostly infects the fins of the female fish . 
 
 = = Uses = = 
 
 The thread @-@ sail filefish is cultured and sold commercially as food in Asian countries , including Korea and Japan . The demand for the fish in Korea is very high , and fisheries often employ the services of fish hatcheries for breeding more of the fish to supplement and enhance the supply of stock . This has been done to such a degree that some . As many as 95 alleles have been found to be unique to one of the populations , resulting from minor variations in certain genes that occur exclusively within either population ; genetic differentiation between S. cirrhifer born in the wild and those bred in a hatchery has apparently occurred . 
 
 