Island Mangrovegoby, Mugilogobius platystomus (Günther 1872)

Other Names: Indonesian Goby, Island Mangrove Goby

An Island Mangrovegoby, Mugilogobius platystomus. Source: Dave Wilson / Aquagreen. License: All rights reserved

A pale greyish to yellowish-brown goby with about 7 dark brown oblique to vertical oval blotches or bars on sides, first dorsal fin with a broad dark streak and a whitish submarginal band, second dorsal-fin with a whitish submarginal band; caudal-fin base with two oval black spots.

Cite this page as:
Martin F. Gomon & Dianne J. Bray, Mugilogobius platystomus in Fishes of Australia, accessed 29 May 2024,

Island Mangrovegoby, Mugilogobius platystomus (Günther 1872)

More Info


Distributed in northern Australia from Darwin NT (131°30'E) to Sarina, QLD (21°28'S) and elsewhere in coastal waters of the tropical west Pacific from the Indo-Australian Archipelago, Singapore and Palau. 
Inhabits small brackish to freshwater streams running through mangroves, rain forests, or swamps.s clear rainforest streams near the sea 


Meristic features: Dorsal fin VI +  I, 7-9; Anal fin I, 7-9; Pectoral fin 14-17; Caudal fin (segmented rays) 15-16, (branched rays) 13-16; TRB 12-18; Gill rakers 3-4 + 7-8 = 10-12; Vertebrae 10-11 + 15-16 = 26. 
Body rather slender, compressed, though less so anteriorly, depth 4.8-7.8 in SL; caudal peduncle compressed. Head depressed, always wider than deep, length 3.1-5.1 in SL; cheeks sometimes inflated. Snout rounded. Anterior nostril in short tube at edge of upper lip, tube directed down and forward, preorbital produced forward to accommodate nostril; posterior nostril oval to rounded near centre of anterior margin of eye. Eyes lateral, high on head, top forming part of dorsal profile. Interorbital broad, flat; unsealed top of head above preopercular margin to snout tip covered with fine villi, sometimes also on preorbital region. Mouth subterminal, slightly oblique; jaws enlarged in males, reaching past rear margin of eye, in females to below front half or middle of eye in females; lips smooth, lower lip free at sides, fused across front; tongue tip blunt to concave. Gill opening extending forward to just under opercle; inner edge of pectoral girdle smooth with no ridge or flange, with low fleshy ridge or raised bumpy flange, or with distinct fleshy knobs or flaps. Jaws with 4-5 rows of teeth; teeth in outer row of upper jaw largest, stout and curved, others very small and sharp, upright except for innermost row of lower jaw larger, stouter and pointing posteriorly.
Body fully scaled, ctenoid scales in two patches on side, narrow wedge posteriorly forward to about gap between dorsal fins, though rarely to behind pectoral fin, second behind pectoral fin; lateral line absent; longitudinal series 39-57; predorsal scales evenly small, reaching forward to above rear preopercular margin or midway between preopercular margin and rear of eyes, 18-30 on dorsal midline. Upper half to two thirds of operculum with small cycloid scales. Cheek naked. Cycloid scales on pectoral base and prepelvic area; if breast scaled, anteriormost region near isthmus, naked; belly scales cycloid or with isolated patch of ctenoid scales under pelvic fins, covering anterior third of belly or less. Head pores absent.
Two dorsal fins; first triangular, tips of second to fourth spines free and usually elongate but not filamentous, longer in males than females; spines often falling short of second dorsal origin when depressed; second dorsal and anal fins low, pointed posteriorly, dorsal rays rarely reaching, and anal rays always failing to reach caudal fin base when depressed. Pectoral fin oval to rounded, all rays but first usually branched. Pelvic fins completely united into disc, short, oval, reaching half to one-third distance to anus. Caudal fin rounded to oval.


To around 5cm SL


Pale greyish brown to yellowish brown, scale margins darkest, whitish grey below, with highly variable dark brown oblique to vertical oval blotches and bars on sides, first slanting over pectoral base and ending on nape above opercle, last just before caudal base with centre intensified as square blotch; small brown, square saddles, blotches and spots crossing dorsal midline, some coalescing with body bars. Nape with brown spots and irregular to vermiculate streaks on either side of midline; interorbital and snout with brown vermiculations; 2 horizontal brown stripes crossing side of head. Pectoral base dusky brown to yellowish, with horizontal dark bar crossing at midpoint. First dorsal fin with proximal third dusky to translucent, centre of fin with blackish streak widening posteriorly to black blotch, outer part of fin whitish to dusky with dusky to blackish margin; free tips of spines dusky to whitish; second dorsal dusky proximally, with submarginal white to translucent band, fin margin dusky to dark grey; proximal two-thirds of fin dusky with about two rows of vertically oriented blackish or brown streaks or oval blotches, two evenly spaced dark brown blotches at base of fin. Anal fin dusky to dark grey with whitish to translucent margin. Caudal fin dusky, membrane darker than rays, forming faint narrow streaks; two slightly obliquely aligned oval black spots at base. Pectoral fin with rays dusky to brown, membranes translucent. Pelvic fins dusky to dark brown, fraenum paler.

Species Citation

Gobius platystoma Günther, 1872, Proc. Zool. Soc. Lond. 1871(3): 664, pl. 63(B). Type locality: Port Mackay, QLD.


Martin F. Gomon & Dianne J. Bray

Island Mangrovegoby, Mugilogobius platystomus (Günther 1872)


Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field Guide to the Freshwater Fishes of Australia.  Perth : Western Australian Museum 394 pp.

Günther, A. 1872. Report on several collections of fishes recently obtained for the British Museum. Proc. Zool. Soc. Lond. 1871(3): 652–675 pls 53–70 

Larson, H.K. 2001. A revision of the gobiid fish genus Mugilogobius (Teleostei: Gobioidei), and its systematic placement.  Rec. West. Aust. Mus. Suppl. 62: 1–233.

Larson, H. 2012. Mugilogobius platystomus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. . Downloaded on 27 September 2013.

McDowall, R.M. 1997. The evolution of diadromy in fishes (revisited) and its place in phylogenetic analysis. Rev. Fish Biol. Fish. 7(4): 443-462.

Quick Facts

CAAB Code:37428191

Conservation:IUCN Least Concern

Depth:0-5 m

Habitat:Brackish to freshwater streams

Max Size:5 cm SL

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