River Blackfish, Gadopsis marmoratus Richardson 1848

Scientific name: Gadopsis marmoratus
Similar species:
A second species in the genus Gadopsis, is also found in freshwater streams of south-eastern Australia. The Two-spined Blackfish, G. bispinosus Sanger 1984 has a more restricted distribution. This species has only two spines in the dorsal fin, while the River Blackfish has 6 to 13.
River Blackfish, <i>Gadopsis marmoratus</i> Click to enlarge image
A 110mm long River Blackfish from the Namoi River drainage, New South Wales, March, 1998 (AMS I.38753-002). Image: Carl Bento
© Australian Museum

Fast Facts

  • Classification
    Genus
    Gadopsis
    Species
    marmoratus
    Family
    Percichthyidae
    Order
    Perciformes
    Class
    Actinopterygii
    Subphylum
    Vertebrata
    Phylum
    Chordata
    Kingdom
    Animalia
  • Size Range
    The River Blackfish grows to 60 cm in length, but individuals this size are uncommon. It is usually seen at sizes up to 45 cm.

Introduction

The River Blackfish occurs in freshwater streams of south-eastern Australia. It has a reduced distribution because of habitat degradation but is common in some areas.

Identification

The River Blackfish may be pale green, yellowish, brown or black in colour. It usually has a marbled pattern with larger dark blotches. The underside is pale yellow, blue or purple-grey. The upper jaw is longer than the lower.

The pelvic fins are positioned under the opercular openings. Both pelvic fins consist of a single branched ray. The spinous portion of the dorsal fin is lower than the soft-rayed portion.

Habitat

The species occurs in freshwater streams, but has a reduced distribution because of habitat degradation. It is still common in some areas.

In New South Wales and the Australian Capital Territory, the species is mostly found in westerly flowing streams. In South Australia it is restricted to an area in the south east of the state. It occurs widely in Victoria, and is found in northern and southern Tasmania.

Distribution

The River Blackfish occurs in south-eastern Australia.

The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Source: Atlas of Living Australia.

Feeding and diet

It eats insects, crustacea and sometimes other fishes.

Other behaviours and adaptations

The River Blackfish is a nocturnal species.

References

  1. Allen, G.R. 1989. Freshwater Fishes of Australia. T.F.H. Publications. Pp. 240.
  2. Jackson, P.D, Koehn, J.D., Lintermans, M & A.C. Sanger. in McDowall, R.M. 1996. Freshwater Fishes of South-Eastern Australia. Reed Books. Pp. 247.
  3. Merrick, J.R. & G.E. Schmida. 1984. Australian Freshwater Fishes. Biology and Management. John R. Merrick. Pp. 409.