Stephanolepis cirrhifer (Temminck & Schlegel, 1850)

Common Name and Size

Stephanolepis cirrhifer, commonly called the thread-sail filefish, reaches a maximum adult length of about 30 centimetres (12 inches).

Dorsal and Anal Fin Structure

Its first dorsal fin is a strong, retractable spine that can fold backwards, while the second dorsal fin and anal fin are soft.

Pectoral and Tail Fin Structure

The species has comparatively small pectoral fins and truncated, fan-shaped tail fins.

Source Description Inconsistency

There is a minor inconsistency in the source description that notes the dorsal and anal fins are colorless, also says the second dorsal, anal, and caudal fins are rounded.

Male Fin Filaments

In males, 1 to 3 soft dorsal fin rays extend as filaments, with the first ray forming a particularly long thread.

Abdominal Spike

Thread-sail filefish also have a small abdominal spike.

Coloration and Patterning

Their base coloration ranges from light brown to grayish to light greenish-beige, with subtle patterning made up of irregular, broken stripes in shades from medium brown to blackish.

Juvenile Shelter

Juvenile thread-sail filefish typically shelter from predators within clusters of drifting seaweed.

Adult Habitat and Social Behavior

Adults usually live near the seabed at depths around 10 metres (33 feet), and are mostly solitary, residing among coral and seaweed.

Migration Pattern

This species is oceanodromous, meaning it migrates entirely within ocean waters between its feeding and spawning grounds, which can be over 100 kilometres (62 miles) apart.

Spawning Season

Its spawning season runs from May to August.

Juvenile Habitat and Diet

Juveniles under 5 centimetres (2.0 inches) live in shallow water, where they feed on small crustaceans, mollusks, and algae.

Trophic Level

The thread-sail filefish is an omnivore that eats both plant and animal matter.

Primary Diet Components

Its diet includes kelp, and consists mainly of amphipods such as gammarids and skeleton shrimp, as well as the seagrass Zostera marina.

Smaller Prey Items

It also feeds on smaller organisms including bryozoans and some species of serpulid tube worms.

Additional Recorded Prey

Additional recorded prey items include fish, isopods, cirripeds, polychaetes, pelecypods, seaweeds of the genus Sargassum, and gelatinous plankton such as the moon jellyfish Aurelia sp. and the giant jellyfish Nemopilema nomurai.

Parasite Host

S. cirrhifer acts as a host for the pennellid copepod parasite Peniculus minuticaudae, which most often infects the fins of female fish.

Commercial Use

The thread-sail filefish is cultured and sold commercially as food in Asian countries including Korea and Japan.

Culinary Use in Korea

In Korea, it is an ingredient in jwipo.

Hatchery Breeding Rationale

Demand for the fish is very high in Korea, so fisheries often use fish hatcheries to breed additional fish to supplement wild stock.

Wild and Hatchery Genetic Differentiation

This hatchery breeding has led to genetic differentiation between wild-born and hatchery-born S. cirrhifer; as many as 95 alleles have been found to be unique to one population, from minor genetic variations that occur exclusively in either population.