text: stephanolepis cirrhifer stephanolepis cirrhifer , commonly known as the thread - sail filefish , is a species of marine fish in the family . 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 " " ( japanese ) and " - 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 . 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 , as 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 - korean - - chi english - file fish , fool fish , porky russian - small striped triggerfish ( ) 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 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 ( " " ) 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 and skeleton shrimp , as well as the seagrass species zostera marina . the fish also feeds upon smaller organisms , including bryozoans and some species of tube worms . thread - sail filefish feed on fish , amphipods , isopods , , polychaetes , pelecypods , seaweeds such as those of the genus sargassum ; and gelatinous plankton , such as the moon jellyfish aurelia sp. and the giant jellyfish . s. cirrhifer is host of the copepod parasite , 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 .