Congolli, Pseudaphritis urvillii (Valenciennes 1832)

Other Names: Freshwater Flathead, Marble Fish, Marbled Flathead, Sand Trout, Sanding, Sandy, Sandy Whiting, Tupong

Congolli, Pseudaphritis urvillii. Source: Rudie H. Kuiter / Aquatic Photographics. License: All rights reserved


A slender mottled brownish fish with a silvery-white underside, a somewhat flattened head with eyes close together near the top, a sharply-pointed snout, two separate dorsal fins, the second long-based and similar to the anal fin. 

Congolli inhabit slow-moving waters of estuaries, rivers and creeks, often lying motionless, partly buried, blending in with the detritus and leaf litter on the bottom. They can easily move between brackish and freshwater habitats.

Video of Spotted Galaxias (Galaxias truttaceus), Common Galaxias (Galaxias maculatus), Freshwater Flathead, Congolli (Pseudaphritis urvillii) and Southern Shortfin Eel (Anguilla australis) in Fotheringate Creek, Flinders Island, Tasmania.

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Bray, D.J. & Thompson, V.J. 2020, Pseudaphritis urvillii in Fishes of Australia, accessed 19 Apr 2024,

Congolli, Pseudaphritis urvillii (Valenciennes 1832)

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Endemic to coastal streams of southern Australia, from about Mogo (New South Wales) to the western side of Spencer Gulf (South Australia), and throughout coastal rivers of Tasmania. Inhabits brackish estuaries and the lower reaches of slow-flowing freshwater streams that are connected to the sea.

Congolli live amongst debris and leaf litter, or beneath logs and overhanging banks in pools and streams. Juveniles often shelter amongst large boulders in estuaries and the lower reaches of streams.

Large individuals are most common at the upstream extent of their range, with males and females appearing to live in different parts of their habitat. Mature adults migrate downstream into estuaries during the autumn and winter to breed. The larvae are carried out to sea, and juveniles usually remain in the lower parts of rivers, slowly moving upstream as they grow.


Dorsal fin VII-IX, 19-22; Anal fin II, 21-22; Pectoral fin 17-19; Pelvic fin I, 5; Lateral line scales 59-66.

Body almost cylindrical, elongate, slender, depth about 6-7 times in SL, somewhat com­pressed posteriorly; dorsal profile almost straight. Head conical, sharply pointed, somewhat depressed. Eyes small, close together, almost on top of head. Mouth rather small, extending back to below about middle of eye; lower jaw longer than upper jaw; both jaws with bands of villiform teeth. Operculum with inconspicuous flattened spine.

Two dorsal fins separated by distinct gap; first short-based, triangular, composed of weak spines; second long-based, composed of rays. Anal fin long-based, opposite and longer than second dorsal fin. Caudal fin slightly rounded. Pectoral fins large, somewhat rounded, reaching back to behind first dorsal fin. Ventral fins thoracic, inserted anterior to base of pectoral fins.

Scales ctenoid, of moderate size, covering head and body. Lateral line uninterrupted, following dorsal profile.


To around 35 cm TL, commonly to 15-20 cm.


Colour varies with habitat. Bluish, purplish or reddish-brown marbled with greenish-brown above, yellowish white to silvery below; dark blotches usually on dorsal surface, some with a dark stripe below the lateral line con­nected at intervals by vertical bars to a broken stripe along the abdomen; head marbled blackish and yellow, sometimes marked with purple and red; two oblique black bars angled posteroventrally from the eye; sometimes a third oblique dark bar in front of eye; eye yellow.

Anal fin pinkish; other fins colourless to pale straw and, except for anal and pelvic fins, with dark, usually brown, spots appearing as dashed lines. Juveniles with evenly-spaced, black saddles on dorsal surface.


Feeds on small fishes and benthic invertebrates, including insects, crustaceans, molluscs and worms. Congolli feed mostly on insects in fresh water and crustaceans in estuaries. This ambush predator often lies buried in sand with only their eyes protruding.


Congolli are catadromous, living in freshwater habitats as adults. During winter months, they undertake downstream spawning migrations. The larvae develop at sea, before returning to freshwater habitats as juveniles.

Congolli are sexually dimorphic in size. Males usually attain a maximum size of 15 cm and are most common in estuaries and brackish waters. Individuals greater than 20 cm in length are nearly always female, and commonly occur in freshwater habitats.

Females migrate downstream to the tidal parts of estuaries to breed during autumn-winter (late April to mid August). where they spawn demersal eggs in sandy and weedy areas. Congolli mature after about 5 years when individuals reach about 15 cm SL.


Until relatively recent times, the species was also a minor part of commercial fisheries in the Lower Lakes of the River Murray, South Australia. Although not targeted commercially now, and rarely large enough, the flesh is excellent eating. Historically, coastal indigenous communities consumed Congolli.


During their lifecycle, Congolli migrate between freshwater and marine habitats. Along with reduced water flows due to climate change, the construction of weirs and barrages may impact populations.


The species is named for Jules Sébastien César Dumont d'Urville, a French explorer and naval officer, who who led the expedition during which the type specimen was collected.

Species Citation

Aphritis urvillii Valenciennes, 1832, Histoire Naturelle des Poissons 8: 484, pl. 243. Type locality: Tasmania


Bray, D.J. & Thompson, V.J. 2020


Atlas of Living Australia

Congolli, Pseudaphritis urvillii (Valenciennes 1832)


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Quick Facts

CAAB Code:37403003

Biology:Migratory, marine larvae

Conservation:IUCN Least Concern

Habitat:Estuarine, freshwater

Max Size:35 cm TL


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