Welch's Grunter, Bidyanus welchi (McCulloch & Waite 1917)

Other Names: Black Bream, Silver Bream

Welch's Grunter, Bidyanus welchi. Source: Douglass F. Hoese. License: All rights reserved


Although this medium to large grunter is similar to the Silver Perch, the two species occur in different drainage systems.

Identifying features:
Body robust with a small head and mouth;
Overal greyish-brown to olive-brown with darker scale margins, silvery below.

Cite this page as:
Martin F. Gomon & Dianne J. Bray, Bidyanus welchi in Fishes of Australia, accessed 27 Oct 2021, https://fishesofaustralia.net.au/home/species/688

Welch's Grunter, Bidyanus welchi (McCulloch & Waite 1917)

More Info


Endemic to internal drainage systems of central Australia including Barcoo River (145º08´E), Diamantina River (139º21´E) and Georgina River (138º15´E), QLD and Lake Eyre drainage, SA (137º00´E), but not recorded from the Northern Territory; tropical, temperate.

Welch's Grunter usually inhabits turbid areas of larger turbid rivers and permanent waterholes. The species is tolerant to high temperatures and salinities.


Meristic features:
Dorsal-fin spines/rays: D XII, 11-12
Anal-fin spines/rays: III, 8-9
Pectoral-fin rays: 16-17
Pelvic-fin spines/rays: I, 5
Vertebrae: 11+14
Gill rakers: 8-9 +1 + 14-17
Vertebrae: 11+14
Transverse scales: 10-12/1/25-27

Body elongate, oblong to ovate, slender, depth 3.1-3.3 in SL, slightly compressed, body width 1.5-1.65 in body depth; dorsal and ventral profiles evenly arched; dorsal profile straight from snout to nape, then convex to dorsal origin, ventral profile evenly arched to ventral insertion, then straight to anus. Head length 3.5-3.8 in SL. Snout elongate, length 3.1-3.3 in HL. Eye width 5.0-6.6 in HL. Interorbital region smooth, flat. Nostrils separated by a distance equal to diameter of posterior nostril. Upper jaw slightly longer than lower; jaw length 3.3-3.65 in HL; gape nearly horizontal; maxillary reaching to vertical through posterior nostril; teeth conic, slightly depressible; outer row enlarged, followed by villiform teeth in bands; no teeth on vomer or palatines. Lacrimal serrate. Preoperculum serrate; serrations largest on angle. Lower opercular spine longer and stronger; reaching nearly to edge of opercular lobe. Cleithrum exposed; serrate along posterior edge; scales on side. Supracleithrum exposed. Posttemporal exposed; serrate along posterior edge.

Scales finely ctenoid; lateral line continuous, smoothly curved; 68-72 scales counted in a series above lateral line; 59-66 scales counted in a series below lateral line; 6-9 scales on caudal; 20-25 predorsal scales to occiput; 2-3 rows of scales in sheath at base of dorsal fin, sheath extending to eighth or ninth dorsal ray; 4 rows of scales in sheath at base of anal fin, sheath extending across base of all rays; cheek scales in 5-7 rows.

Dorsal fin continuous, base 1.8-2.0 in SL; spinous portion arched; first spine very short; fifth or sixth longest, 2.1-2.5 in HL, those following decreasing in length to ultimate; longest dorsal spine longer than longest dorsal ray, 2.9-3.7 in HL; posterior edge of soft dorsal slightly convex. Second anal spine very strong, 2.0-2.3 in HL, longer than third, about twice as long as first, as long as longest anal ray, 1.9-2.2 in HL. Pectoral fins pointed; fifth ray longest. Ventral fins pointed; first ray longest; reaching one-half distance to anus. Caudal fin emarginate.


To 40 cm SL but commonly to 23 cm SL.


Yellowish or brownish overall, slightly darker above; body dusky, each scale with a spot of heavier pigmentation along edge of scale pocket; on caudal peduncle, these join together in some specimens to form irregular longitudinal vermiculations. Median fins with slightly dusky membranes. Caudal fin dusky at base. Pelvic fins slightly dusky. Pectoral fins colorless.


Carnivore- feeds on on small fishes, shrimps and worms.


Oviparous pelagic spawners that migrate upstream to breed during summer flooding. Females spawn pelagic eggs during warmer months. Larvae hatch after 30 hours at around 24-28 cm. Little is known of the biology and ecology of this species.


Similar Species

Distinguished from all other terapontids in having depressible but unflattened teeth, 20-25 predorsal scales to the occiput, maximum body width 1.5 -1.7  in body depth, 68-72 scales counted in a series above lateral line, and  59-66  below. 


Bidyanus is derived from the Aboriginal word Bidyan, meaning 'fish'. The species is named welchi after E. J. Welch, a member of the Burke and Wills expedition.

Species Citation

Therapon welchi McCulloch & Waite, 1917, Trans. R. Soc. S. Aust. 41: 472. Type locality: Coopers Creek, near Innamincka, South Australia.


Martin F. Gomon & Dianne J. Bray

Welch's Grunter, Bidyanus welchi (McCulloch & Waite 1917)


Allen, G.R. 1989. Freshwater Fishes of Australia.  Neptune, New Jersey : T.F.H. Publications 240 pp. pls 1–63.

Allen, G.R., Midgley, S.H. & Allen, M. 2002. Field guide to the freshwater fishes of Australia.  Perth : Western Australian Museum 394 pp..

McCulloch, A.R. & Waite, E.R. 1917. Results of the South Australian Museum expedition to Strzelecki and Coopers Creeks; Pisces. Trans. R. Soc. S. Aust. 41: 472–475 figs 1–2

Merrick, J.R. & Schmida, G.E. 1984. Australian Freshwater Fishes Biology and Management.  Sydney : J.R. Merrick 409 pp. figs 280 col. figs.

Unmack, P.J. 2001. Biogeography of Australian freshwater fishes. Journal of Biogeography 28: 1053-1089

Vari, R.P. 1978. The terapon perches (Percoidei, Terapontidae) a cladistic analysis and taxonomic revision. Bull. Amer. Mus. Nat. Hist. 159(5): 175–340 figs 1–94.

Wager, R. & Unmack, P.J. 2000. Fishes of the Lake Eyre catchment of central Australia. Brisbane : Department of Primary Industries Queensland Fisheries Service. 88 pp. 

Quick Facts

CAAB Code:37321010

Habitat:Freshwater rivers, billabongs

Max Size:40 cm SL


Species Image Gallery

Species Maps

CAAB distribution map