Twospot Flathead, Onigocia bimaculata Knapp, Imamura & Sakashita 2000

A Twospot Flathead, Onigocia bimaculata, on Mantis Reef, Great Barrier Reef, Queensland, November 2001. Source: Erik Schlogl / License: CC by Attribution-NonCommercial

A small flathead with two small blackish spots near the margin of the first dorsal fin, and the pelvic fins with a large black spot on the upper surface near the base and usually one or two small black spots or bands distally.

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CSIRO Marine & Atmospheric Research, Onigocia bimaculata in Fishes of Australia, accessed 13 Jul 2024,

Twospot Flathead, Onigocia bimaculata Knapp, Imamura & Sakashita 2000

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In Australia only known from Lihou Reef, Coral Sea. Internationally recorded from the Gulf of Aqaba, Comoro Island and Mauritius to southern Japan, the Philippines, Caroline Islands, New Caledonia, Fiji, Tonga, American Samoa and the Society Islands. Demersal in bays and coastal waters at depths of 3-30 m.


Dorsal fin VIII-IX (usually VIII), 10-12 (usually 11); Anal fin 10-12 (usually 11); Caudal fin 8-9 (usually 9); Pectoral fin 19-22 (usually 19); Pelvic fin I, 5; Lateral line scales (pored) 32-39 (usually 36).

Body elongate, depressed. Head large (length 33-42% SL), depressed, with several low ridges, mostly bearing spines; eyes large (10-13% SL) ocular flap absent; villiform teeth in bands on jaws and palatines, in two separate patches on vomer; tooth band on upper jaw with a distinct notch; three preopercular spines, uppermost longest; well developed interopercular flap present; gill rakers 6-9 on lower limb of first arch. Scales ctenoid, some cycloid scales ventrally; pored scales in lateral line 32-39 (usually 36), the anterior 2-4 (usually 2) scales with a distinct spine. First dorsal fin spinous, first spine short, following spines much longer. Second dorsal fin with moderately long base, anterior rays longest, nearly as long as longest first dorsal spines. Anal fin similar in shape, and opposite and slightly longer-based than second dorsal fin. Caudal fin truncate to slightly rounded. Pectoral fins moderately small. Pelvic fins long, based below centre of pectoral fins.


Maximum length at least 66 mm SL.


Body light tan above, back crossed dorsally by 4 or 5 indistinct saddles. Fins mostly clear. Spinous dorsal fin bearing 2 small black spots near the margin, the largest behind the first long spine, the smallest behind the third long spine. Caudal fin bearing a faint submarginal dark band. Pelvic fin with a prominent black blotch near base on upper surface and often 2 or 3 smaller black blotches or bars distally.


May be caught incidentally over coral sands.


Species Citation

Onigocia bimaculata Knapp, Imamura & Sakashita, J.L.B. Smith Inst. Ichthyol. Spec. Publ. Minna I., Ryukyu Is., Japan.


CSIRO Marine & Atmospheric Research

Twospot Flathead, Onigocia bimaculata Knapp, Imamura & Sakashita 2000


Eschmeyer, W.N. (2008) The Catalogue of Fishes on-line. (California Academy of Sciences: San Francisco) Available from: (10 March, 2008).

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.

Knapp, L.W., Imamura, H. & Sakashita, M. (2000) Onigocia bimaculata, a new species of flathead fish (Scorpaeniformes: Platycephalidae) from the Indo-Pacific. J.L.B. Smith Institute of Ichthyology Special Publication No. 64: 1-10.

Quick Facts

CAAB Code:37296050

Danger:Venomous spines

Depth:1-30 m


Max Size:7 cm SL

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