Twospine Blackfish, Gadopsis bispinosus Sanger 1984


Other Names: Two-spined Blackfish

Twospine Blackfish, Gadopsis bispinosus. Source: Tarmo Raadik. License: All rights reserved

Summary:
Very similar to the River Blackfish, with two rather than three dorsal-fin spines. Twospine Blackfish have a marbled or leopard-like pattern of greenish, yellow and brown markings, with white margins on the dorsal and anal fins.

Cite this page as:
Bray, D.J. & Gomon, M.F. 2017, Gadopsis bispinosus in Fishes of Australia, accessed 14 Nov 2018, http://fishesofaustralia.net.au/home/species/3876

Twospine Blackfish, Gadopsis bispinosus Sanger 1984

More Info


Distribution

Endemic to the Murray-Darling Basin Catchment, and found in the upper reaches of the Murray River system of northeastern Victoria, east of King Parrot Creek, the Australian Capital Territory (ACT) and southeastern New South Wales (NSW). Although locally abundant in some areas, many populations are highly fragmented, and the species no occurs in some catchments of the ACT and NSW.

Twospine Blackfish live near the bottom amongst rocks and boulders at higher altitudes in clear flowing streams with gravelly bottoms and abundant instream vegetation, fallen timber, debris and boulders. They have small home ranges of up to 30 m, and are nocturnally active, returning to shelter in the same area around dawn each morning.

While adults are usually solitary, juveniles often aggregate among woody debris and leaf litter.

Features

Dorsal fin I-III, 35-38; Anal fin III, 17-20; Pectoral fin 15-18; Pelvic fin 1; Caudal fin 30.
Body slender, elongate and slightly compressed; greatest body depth around 0.19 of SL; caudal peduncle shallow and compressed; head narrow and slightly elongated, length around 0.24 of SL; snout rounded, short, length around 0.24 of head length; mouth large; eye moderate, diameter 0.19 of HL, dorso-lateral; jaws long, reaching back to below the posterior half of the eye; lips fleshy; jaw teeth numerous, premaxilla with an outer row of large conical teeth, within which there is a band of minute cardiform teeth becoming narrower posteriorly; palatines and vomer with numerous small cardiform teeth; 2 prominent rows of laterosensory pores and numerous smaller pores on head; nostrils prominent, one halfway along snout with fleshy tubular opening, other simple, just in front of eye.
Scales tiny, lateral line well developed with around 48 tubercles; covered with a thick mucous coating.
Single long dorsal fin, inserted behind level of the pectorals bearing 2, rarely 1 or 3, weakly-calcified, slender spines and 35-38; anal fin long, origin about half way along body with 3, strongly-calcified, stout, spines and 17-20; caudal fin rounded with around 30 rays, half of which are branched; pelvic fins reduced to a single fleshy bifid ray inserted jugularly; pectoral fins inserted laterally, below opercular spine, rounded, moderate in size.

Size

To around 30 cm SL.

Colour

Colour variable, brownish overall with 2-3 rows of dark brown blotches running entire length of body, extending onto dorsal and caudal fins. Brown blotches separated by paler areas; ventral surface uniformly pale from pelvic origin to anal origin. Outer edge of dorsal, anal and caudal fins white, often bordered on inner margin by an intense dark stripe. Fin rays in dorsal, anal and caudal often bright yellow in live specimens. Colour pattern more distinct in juveniles, often being obscured by intensified pigmentation in older specimens. In life, able to intensify or subdue base colouration to suit surroundings.

Feeding

Feeds mostly on aquatic insect larvae, terrestrial invertebrates; occasionally preys on small fishes and crayfish.

Biology

The sexes are separate and fertilisation is external. Breeding occurs from late spring to early summer and females spawn a single demersal egg mass of 80-420 eggs onto a hard sediment-free surface. The eggs are large (~3.5 mm diameter), yolky and adhesive. The male parent guards and fans the eggs until the larvae hatch after about 16 days. He continues caring for the fry until they leave the spawning site after about three weeks.

Fisheries


Conservation

ACT : Endangered.
Twospine Blackfish are highly susceptible to sedimentation and are preyed upon by introduced trout.

Remarks


Similar Species

Differs from Gadopsis marmoratus in having two, or rarely one or three, dorsal-fin spines, and a prominent white margin on the dorsal, anal and caudal fins. G. marmoratus has between six and thirteen spines in the dorsal fin and lacks a prominent white fringe on the fins.

Etymology


Species Citation

Gadopsis bispinosus Sanger 1984, Proc. R. Soc. Vict. 96(2): 93, fig. 1. Type locality: west branch of the King River, Victoria

Author

Bray, D.J. & Gomon, M.F. 2017

Resources

Australian Faunal Directory

Twospine Blackfish, Gadopsis bispinosus Sanger 1984

References


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

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

Broadhurst, B., Dyer, J., Ebner, B., Thiem, J. & Pridmore, P. 2011. Response of two-spined blackfish Gadopsis bispinosus to short-term flow fluctuations in an upland Australian stream. Hydrobiologia 673: 63-77, doi:10.1007/s10750-011-0750-0 Abstract

Broadhurst, B.T., Lintermans, M., Thiem, J.D., Ebner, B.C., Wright, D.W. & Clear, R.C. 2012. Spatial ecology and habitat use of two-spined blackfish Gadopsis bispinosus in an upland reservoir. Aquatic Ecology 46: 297-309, doi:10.1007/s10452-012-9401-4 Abstract

Curmi, T.J. 1996. Habitat use and diet of River Blackfish (Gadopsis marmoratus) and Two-spined blackfish (Gadopsis bispinosus) in Tallangatta Creek. BSc (Hons) thesis, La Trobe University, Bundoora, Victoria.

Hammer, M.P., Unmack, P.J., Adams, M., Raadik, T.A. & Johnson, J.B. 2014. A multi-gene molecular assessment of cryptic biodiversity in the iconic freshwater blackfishes (Teleostei: Percichthyidae: Gadopsis) of southeastern Australia. Biological Journal of the Linnean Society 111: 521-540, DOI: https://doi.org/10.1111/bij.12222 Open access

Jackson PD. 1978. Spawning and early development of the river blackfish, Gadopsis marmoratus Richardson (Gadopsiformes: Gadopsidae), in the McKenzie River, Victoria. Australian Journal of Marine and Freshwater Research 29: 293–298.

Jackson, P.D., Koehn, J.D., Lintermans, M. & Sanger, A.C. 1996. Family Gadopsidae, pp 186-190. In McDowall, R.M., (ed.) Freshwater fishes of south-eastern Australia. Second edition. Reed Books, Australia.

Jenkins, A., Kullander, F.F. & Tan, H.H. 2009. Gadopsis bispinosus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. . Downloaded on 2 June 2012.

Koehn, J.D. 1987. Artificial habitat increases abundance of Two-spined Blackfish Gadopsis bispinosus in Ovens River, Victoria. Arthur Rylah Institute for Environmental Research Technical Report Series No. 56. Department of Conservation, Forests and Lands, Melbourne, 20 pp.

Koehn, J.D. 1990. Distribution and conservation status of the Two-spined Blackfish Gadopsis bispinosus in Victoria. Proceedings of the Royal Society of Victoria 102(2): 97-103.

Lintermans, M. 1998. The ecology of the Two-spined Blackfish Gadopsis bispinosus (Pisces: Gadopsidae). MSc thesis, Division of Botany & Zoology, Australian National University.

Lintermans M. 2012. Managing potential impacts of reservoir enlargement on threatened Macquaria australasica and Gadopsis bispinosus in southeastern Australia. Endangered Species Research  16: 1–16, DOI: https://doi.org/10.3354/esr00382 Open access

Lintermans, M. & Rutzou, T. 1990. A new locality for the Two-spined Blackfish Gadopsis bispinosus outside Victoria. Victorian Naturalist 107: 26-27.

Lintermans M. 2007. Fishes of the Murray-Darling Basin: An Introductory Guide. Murray Darling Basin Commission. 157 pp.

McDowall, R.M. (ed.) 1996. Freshwater Fishes of South-eastern Australia. Sydney : Reed Books 247 pp.

Miller, A.D., Waggy, G., Ryan, S.G. &Austin, C.M. 2004. Mitochondrial 12S rRNA sequences support the existence of a third species of freshwater blackfish (Percicthyidae: Gadopsis) from south-eastern Australia. Memoirs of Museum Victoria 61(2): 121-127.

O’Connor, J.P. & Zampatti, B.P. 2006. Spawning season and site location of Gadopsis bispinosus Sanger (Pisces: Gadopsidae) in a montane stream of southeastern Australia. Transactions of the Royal Society of South Australia 130: 227-232.

Ovenden JR, White RWG, Sanger AC. 1988. Evolutionary relationships of Gadopsis spp. inferred from restriction enzyme analysis of their mitochondrial DNA. Journal of Fish Biology 32: 137–148, DOI: 10.1111/j.1095-8649.1988.tb05342.x Abstract

Sanger, A.C. 1984. Description of a new species of Gadopsis (Pisces: Gadopsidae) from Victoria. Proc. R. Soc. Vict. 96(2): 93–97.

Sanger, A.C. 1986. The evolution and ecology of the Gadopsis marmoratus complex. PhD. thesis, University of Melbourne, Victoria.

Sanger, A.C. 1990. Aspects of the life history of the Two-spined Blackfish Gadopsis bispinosus in King Parrot Creek, Victoria. Proceedings of the Royal Society of Victoria 102(2): 89-96.

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

Waters JM, Lintermans M, White RWG. 1994. Mitochondrial DNA variation suggests river capture as a source of vicariance in Gadopsis bispinosus (Pisces: Gadopsidae). Journal of Fish Biology 44: 549–551, DOI: 10.1111/j.1095-8649.1994.tb01232.x Abstract.

Quick Facts


CAAB Code:37373002

Conservation:IUCN Least Concern; ACT Endangered

Habitat:Clear upland streams

Max Size:30 cm SL

Native:Endemic

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