Bony fish · Perciformes · Polynemidae

Sixfinger Threadfin

Polydactylus sexfilis

Least Concern

The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary

A threadfin with a silvery body and a blunt snout, with six free rays beneath the pectoral fin that it uses as tactile fingers to track prey buried in the sand of the surf zone. It is a highly prized fish in Hawaii, where it is known as moi.

Weight

up to 3.2 kg

Size

30 cm – 60 cm

Diet

Carnivore

Feeds mainly on other animals.

Sighting difficulty

Easy

OceanCarnivore Fish Ocean

8countries

Fun facts

The six threads that give it its name are pectoral fin rays that have become independent and work as sensory fingers feeling the bottom.
It is a protandrous hermaphrodite: it matures first as a male, and the largest individuals are females.
In ancient Hawaii eating it was reserved for the chiefs, and today it is one of the flagship species of the islands' aquaculture.
It is a protandrous hermaphrodite: male first and female later, with an intermediate hermaphrodite phase.
Spawning is governed by the phases of the moon.
Its Hawaiian name, moi, means fish of kings; it was reserved for the nobility and today it is one of the flagship species of Hawaiian aquaculture.
Coastal populations fell sharply over the last thirty or forty years, which has driven breeding and restocking programmes.

Life cycle & biology

Habitat & environment: Shallow sandy and surf waters on Indo-Pacific coasts
Sexual maturity: They mature as males between 20 and 25 cm fork length and change into fertile females between 30 and 40 cm

Sources consulted: FishBase (Froese & Pauly, eds.); Lista Roja de la UICN (evaluación de 2023); Motomura (2004), FAO; Center for Tropical and Subtropical Aquaculture