Dorsal fin with 11 spines and 14-15 rays. Anal fin with 3 spines and 8 rays. Pectoral fin with 18-19 rays. Body depth 2.7-3.1 in standard length. Dorsal head profile smoothly convex. Inter- orbital area flat. Mid-lateral body scales mostly ctenoid, not covered by skin. Rear nostril diameter about twice diameter of front nostrils. Caudal fin rounded. Color is Mottled brown, covered with small dark spots. Head and body with fairly distinct dark blotches, blotch on top of caudal peduncle brownish-black and conspicuous.
This species prefers shallow coral-rich areas in lagoons and outer reefs and is more abundant around islands, particularly atolls. It is usually solitary or in small schools (Heemstra and Randall 1993). Maximum reported length is about 90 cm, but is typically no larger than 70 cm total length. The species appears to be gonochoristic (Rhodes et al. 2011), and hermaphroditism has been suggested, but not confirmed. Data from the Great Barrier Reef, New Caledonia, Pohnpei and Papua New Guinea suggest an age of sexual maturation at about four years and a maximum overall age of 42 years (Mapleston et al. 2009, Rhodes et al. 2011, K. Rhodes and B. Taylor unpublished data 2016). In Papua New Guinea, maximum age was 22 years and age at maturity was 6.8 years (P. Waldie unpublished data 2017). Applying an age at maturity of four and longevity of 42, its estimated generation length is 23 years based on the following equation recommended by the IUCN Red List methods: Age at first reproduction + (Age at last reproduction – age at first reproduction)/2.
This species migrates using regular reproductive migratory corridors of varying distances to form seasonal spawning aggregations that can contain hundreds to a few thousand individuals with a maximum reported at two sites (Pohnpei and the Tuamotus) of 20,000 (Robinson et al. 2008, Sadovy de Mitcheson 2011, Bijoux et al. 2013, K. Rhodes unpublished data 2016). A study in Pohnpei showed that spawning occurred on several nights during the full moon period during each of the months between February and April (Rhodes and Sadovy 2002a and b). Aggregation sites are known from Palau, Pohnpei (Micronesia), Mauritius, Cook Islands, Solomon Islands, Seychelles, Fiji, Papua New Guinea, Maldives, Indonesia, French Polynesia (Tuamotus), New Caledonia, the Great Barrier Reef Marine Park (Australia) and probably also in Malaysia. In a study conducted in Palau, mature females were between 30 and 47 cm fork length, mature males between 34 and 50 cm and immature fish between 24 and 29 cm, which indicates that sexual maturation occurred between about 29 and 30 cm (Johannes et al. 1999). Sexual maturation in 50% of females occurred at about 27 cm standard length in Pohnpei and there was no evidence for sex change (Rhodes and Sadovy 2002a and b). In Chuuk, 50% sexual maturity for females occurred at about 31 cm total length (K. Rhodes unpublished data 2016). It has a relatively low population turnover rate, and a natural mortality of 0.144 yr-1 (Rhodes et al. 2011).
Overfishing by commercial and recreational fisheries is a major threat to this species. Spawning aggregation sites and timing are often widely-known by fishers, and easily accessed in outer reef passages. In some locations, the species utilizes predictable reproductive migratory corridors to and from aggregation sites, which increases its susceptibility to exploitation. Given its continued high-value in the international market, and the fact that fishing is insufficiently managed in most areas, it is inferred that populations will continue to decline, especially due to heavy fishing of spawning aggregations and the high frequency of juveniles in the catch (Sadovy de Mitcheson and Colin 2012). Secondarily, degradation of the coral reefs that this species inhabits is expected to increase due to impacts from climate change, including rising water temperatures. Land-based activities, such as logging and coastal development also contribute to reef degradation.