Environment: milieu / climate zone / depth range / distribution range
Marine; reef-associated; depth range 0 - 180 m (Ref. 89972). Tropical; 26°C - 29°C (Ref. 27115); 35°N - 33°S, 30°E - 128°W
Indo-Pacific: Red Sea and East Africa (Ref. 3145) to the Hawaiian, Marquesas and Tuamoto islands, north to southern Japan, south to Lord Howe and Rapa islands. Presence in Somalia to be confirmed (Ref. 30573).
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 70.0 cm FL male/unsexed; (Ref. 9710); common length : 50.0 cm TL male/unsexed; (Ref. 3146); max. reported age: 55 years (Ref. 118238)
soft rays: 27 - 30. This species is characterized by the following: body depth vary from about 2.0 in SL (in subadults) to 2.4-2.6 (adults) in SL; with a tapering, bony, horn on forehead of adults projecting anteriorly at level of eye but not extending in front of mouth (horn first as a bump on forehead at a length of about 12 cm); dorsal profile from snout to horn straight, angle of about 45°; 2 peduncular plates with well-developed forward-curving knife-like spines; emarginate caudal fin when young, truncate with filamentous lobes in adult; males apparently with longer horn, larger peduncular keels and longer caudal filaments than females of the same size; body yellowish to olivaceous gray dorsally, paler ventrally, with blue peduncular plates and keel spines; lips whitish or blue; blue area is sometimes present around pectoral fin; dorsal and anal fins yellowish with narrow blue margins; caudal fin orangish basally, shading to gray, with a broad, pale greenish posterior border and caudal filaments are edged in blue; one transient color phase is a blotchy pale greenish zone below the spinous portion of dorsal fin that narrows and ends beneath the pectoral fin (Ref. 27362).
Adults inhabit channels, moats, lagoon and seaward reefs with strong surge (Ref. 48637). Benthopelagic (Ref. 58302). Typically occurring in small groups. Sometimes solitary (Ref. 90102). Juveniles in shallow protected bays and harbours (Ref. 48637). Mainly diurnal, feed on coarse leafy brown algae like Sargassum. Pair-spawning has been observed. Minimum depth reported taken from Ref. 128797.
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Spawn in pairs (Ref. 240).
Myers, R.F., 1991. Micronesian reef fishes. Second Ed. Coral Graphics, Barrigada, Guam. 298 p. (Ref. 1602)
IUCN Red List Status (Ref. 126983)
Threat to humans
Reports of ciguatera poisoning (Ref. 4795)
Fisheries: commercial; gamefish: yes; aquarium: commercial
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Preferred temperature (Ref. 123201
): 23.4 - 28.8, mean 27.4 °C (based on 1536 cells).
Phylogenetic diversity index (Ref. 82804
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.02344 (0.01735 - 0.03168), b=2.95 (2.86 - 3.04), in cm total length, based on LWR estimates for this species (Ref. 93245
Trophic level (Ref. 69278
): 2.2 ±0.11 se; based on food items.
Resilience (Ref. 120179
): Low, minimum population doubling time 4.5 - 14 years (K=0.14).
Prior r = 0.28, 95% CL = 0.16 - 0.49, Based on 3 stock assessments.
Fishing Vulnerability (Ref. 59153
): Low to moderate vulnerability (32 of 100).
Climate Vulnerability (Ref. 125649
): Very high vulnerability (80 of 100).
Nutrients (Ref. 124155
): Calcium = 33.3 [16.8, 58.2] mg/100g; Iron = 0.554 [0.285, 1.039] mg/100g; Protein = 18.4 [17.1, 19.7] %; Omega3 = 0.109 [0.065, 0.196] g/100g; Selenium = 58.8 [29.8, 118.5] μg/100g; VitaminA = 21.5 [5.0, 90.1] μg/100g; Zinc = 1.03 [0.66, 1.54] mg/100g (wet weight);