Mud Flathead, Ambiserrula jugosa (McCulloch 1914)

A Mud Flathead, Ambiserrula jugosa, in Nelson Bay, Port Stephens, New South Wales, October 2014. Source: Tony Strazzari / License: CC By Attribution-NonCommercial


A brown to greyish flathead with about four broad dark bands on the back, 4 or 5 dark blotches on the side of head, a broad dark bar below the eye, and dark blotches and streaks on the lower sides. The Mud Flathead also has long branched iris lappets on the eyes.

Cite this page as:
CSIRO Marine & Atmospheric Research & Bray, D.J. 2021, Ambiserrula jugosa in Fishes of Australia, accessed 23 Jul 2024,

Mud Flathead, Ambiserrula jugosa (McCulloch 1914)

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Coastal waters of eastern Australia from the Great Barrier Reef, NW of Cape Melville, Queensland, to Botany Bay, New South Wales. Inhabits silty and sandy bottoms in estuaries and shallow coastal waters, often buried in the substrate during the day. 


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

Body elongate, moderately depressed. Head large (length 38-39% SL), moderately depressed, lower edge bicarinate; eyes large (22-25% HL), iris lappet with crenate or short branches; mouth large, rear edge reaching to slightly posterior of front edge of eye; teeth very small, slightly larger and in two separate patches on vomer, a narrow band on each palantine; usually three preopercular spines, upper and middle spine short, lower small and accessory; supraorbital ridge serrate, with small spines clustered posteriorly; a series of small preorbital spines present; preocular spines usually clustered, with one larger spine and several smaller spines around its base; suborbital ridge with numerous small serrations; interopercular flap truncated, tongue-shaped; 6 gill rakers on first gill arch rudimentary; anterior nostril with a short tentacle.

Scales moderately large, finely ctenoid, covering body and most of head behind eyes; lateral line scales raised but not larger than adjacent scales on side, anterior 10-25 with a small spine or ridge, pores with 2 openings; oblique rows of scales above lateral line about equal to number of lateral-line scales.

First dorsal fin spinous with short base, first spine very short, separated, following spines longer but weak, third longest. Second dorsal fin with moderately long base, second ray longest, others decreasing in length. Anal fin similar in shape, commencing just posterior to second dorsal-fin origin, rays shorter than dorsal rays and increasing in length posteriorly. Caudal fin broadly rounded. Pectoral fins large, broadly rounded, posterior margin not falcate. Pelvic fins long, based below centre of pectoral fins.


Maximum length at least 21 cm.


Brown or grey dorsally; 4 or 5 dark blotches on side of head, broad dark bar below eye, lips with dark blotches; about 4 dark cross bands dorsally, lower lateral body with dark blotches and streaks; pale ventrally.

First dorsal fin with a dark submarginal band, spines with dark spots; anal fin pale anteriorly, dusky posteriorly; other fins with brown spots (forming vertical bands on caudal fin).


Presumably feeds mostly on fishes.


Taken only as bycatch by trawlers operating in shallow coastal waters.


Previously referred to in Australia as Suggrundus jugosus and Insidiator jugosus.

Species Citation

Insidiator jugosus McCulloch, 1914, Biol. Results "Endeavour" 2(3): 144, pl. 30 (fig. 2), fig. 11, off Hervey Bay, Queensland.


CSIRO Marine & Atmospheric Research & Bray, D.J. 2021


Mud Flathead, Ambiserrula jugosa (McCulloch 1914)


Barnes, L.M., Gray, C.A. & Williamson, J.E. 2011. Divergence of the growth characteristics and longevity of coexisting Platycephalidae (Pisces). Marine and Freshwater Research 62: 1308-1317.

Barnes, L.M., Gray, C.A. & Williamson, J.E. 2021. Reproductive characteristics of Ratabulus diversidens and Ambiserrula jugosa (Pisces: Platycephalidae) from continental shelf waters of south-eastern Australia. Journal of the Marine Biological Association of the United Kingdom 101(4): 725-734

Hutchins, J.B. & Swainston, R. 1986.Sea Fishes of Southern Australia. Complete field guide for anglers and divers. Perth : Swainston Publishing 180 pp.

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

Johnson, J.W. 1999. Annotated checklist of the fishes of Moreton Bay, Queensland, Australia. Memoirs of the Queensland Museum 43(2): 709-762.

Knapp, L.W. 1999. Family Platycepalidae. pp. 2385-2421 in Carpenter, K.E. & Niem, T.H. (eds). The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 4 2069-2790 pp.

Kuiter, R.H. 1993. Coastal Fishes of South-eastern Australia. Bathurst : Crawford House Press 437 pp.

Kuiter, R.H. 1996. Guide to Sea Fishes of Australia. New Holland. 408 pp.
Kuiter, R.H. 2000. Coastal Fishes of South-eastern Australia. Gary Allen. 469 pp.

McCulloch, A.R. 1914. Report on some fishes obtained by the F.I.S. Endeavour on the coasts of Queensland, New South Wales, Victoria, Tasmania, South and South-Western Australia. Part 2. Biological Results of the Fishing Experiments carried on by the F.I.S. Endeavour 1909-1914 2(3): 77-165 figs 1-15 pls 13-34

Quick Facts

CAAB Code:37296041

Danger:Venomous spines

Depth:5-85 m

Habitat:Estuaries, coastal waters

Max Size:21 cm


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