Broadhead Flathead, Sunagocia arenicola (Schultz 1966)

Other Names: Sand Flathead

A Broadhead Flathead, Sunagocia arenicola, from the Raja Ampat Islands, West Papua, Indonesia. Source: Gerald R. Allen / FishBase. License: All rights reserved


A brownish flathead with 4-5 faint bands across the back, and lighter and darker blotches, flecks, mottling and marbling to match their sandy surroundings. Broadhead Flathead are well-camouflaged ambush predators and bury themselves in sandy areas around coral reefs.

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CSIRO Marine & Atmospheric Research, Sunagocia arenicola in Fishes of Australia, accessed 19 May 2024,

Broadhead Flathead, Sunagocia arenicola (Schultz 1966)

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Widespread on the continental slope in the Indo-Pacific, from East Africa and the Gulf of Aden, to Fiji and the Marshall Islands, and south to the northern Great Barrier Reef and Torres Strait, Queensland, Australia. Broadhead Flathead usually bury themselves in the sandy fringes of coral reefs, in 3-30 m.


Dorsal fin IX or I,VIII, 11-13 (usually 12); Anal fin 11-13 (usually 12); Pectoral fin 19-22 (usually 21); Pelvic fin I, 5; Lateral line 50-55 (usually 52 or 53).

Body elongate, depressed. Head large (length 32-35% SL), moderately depressed; a single preocular spine; supraorbital ridge smooth over anterior half of eye, with about 4 or 5 spines posteriorly; suborbital ridge smooth anteriorly, about 4 or 5 spines posteriorly; least interorbital width 7.9-15.1% HL; teeth on vomer in two separate patches; Lips smooth, lacking papillae on edges; preopercular spines 2 or 3 (usually 3), upper longest, rarely reaching past half-way to posterior margin of opercle, not bearing a supplementary spine, Base of lower opercular spine concealed by scales; interopercular not extended anteroventrally, without lobes; total gill rakers on first gill arch 5-7 (usually 6).

Oblique scale rows slanting downward and backward above lateral line about equal to number of lateral-line scales. Lateral-line scales 50-55 (usually 52 or 53), anterior 1-3 (usually 1 or 2) lateral-line scales bearing a small spine.

First dorsal fin spinous with moderately long base, first spine very short, detached, following spines much longer. Second dorsal fin with moderately long base, only slightly longer than first, anterior rays longest, nearly as long as longest first dorsal spines. Anal fin similar in shape, opposite and slightly longer-based than second dorsal fin. Caudal fin slightly rounded posteriorly. Pectoral fins moderate in length, rounded posteriorly. Pelvic fin long, reaching beyond origin of anal fin.


To at least 37 cm TL, commonly to 25 cm TL.


Dorsal head and body tan, mottled with small dark flecks, 4 or 5 vague bands across back, some specimens with a marbled pattern of small dark and light blotches dorsally; whitish ventrally. Fins with numerous small brown dots.


Ambush predators, feeding mostly on crabs and prawns, and also on fishes.


The sexes are separate and fertilisation is external. Little is known of the biology of the Broadhead Flathead.


Likely taken in trawls, or occasionally caught on hook and line.

Species Citation

Thysanophrys arenicola Schultz, In Schultz et al., 1966, Bull. U.S. Natl. Mus. 202: Lagoon reef at Naen I., Rongelap Atoll, western Pacific.


CSIRO Marine & Atmospheric Research

Broadhead Flathead, Sunagocia arenicola (Schultz 1966)


Allen, G.R. & Erdmann, M.V. 2012. Reef fishes of the East Indies. Perth : Tropical Reef Research 3 vols, 1260 pp.

Hoese, D.F., Bray, D.J., Paxton, J.R. & Allen, G.R. (2006) Fishes. In: P.L. Beesley & A. Wells (eds) Zoological Catalogue of Australia Volume 35. Parts 1-3. Australian Biological Resources Study and CSIRO Publishing, 2248 pp.

Imamura, H. 1996. Phylogeny of the family Platycephalidae and related taxa (Pisces: Scorpaeniformes). Species Diversity 1(2): 123-233.

Knapp, L.W. (1999) Family Platycephalidae, flatheads, pp. 2385-2421. In: K.E. Carpenter & V.H. Niem (eds). FAO Species Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific. Volume 4: Bony Fishes Part 2 (Mugilidae to Carangidae). Food and Agriculture Organization of the United Nations, Rome.

Knapp, L.W. & Imamura, H. (2004) Sunagocia sainsburyi, a new flathead fish (Scorpaeniformes: Platycephalidae) from northwestern Australia. Proceedings of the Biological Society of Washington 117(4): 545-550.

Randall, J.E., G.R. Allen & R.C. Steene. 1990. Fishes of the Great Barrier Reef and Coral Sea. University of Hawaii Press, Honolulu, Hawaii. 506 pp.

Schultz, L. P., L.P. Woods & E.A. Lachner (1966) Fishes of the Marshall and Marianas islands. Vol. 3. Families Kraemeriidae through Antennariidae. Bulletin of the United States National Museum 202(3): 124-148.

Quick Facts

CAAB Code:37296043

Danger:Venomous spines

Depth:1-30 m

Habitat:Reef associated, sandy areas

Max Size:37 cm TL (commonly 25 cm)

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