How to Identify River Blackfish

To identify River Blackfish (Gadopsis marmoratus), look at these key features.

Physical Characteristics

Body shape

eel-like

Coloration

Highly variable, typically dark brown to olive-green with irregular, dark mottling or blotches, providing camouflage. The belly is usually paler. Coloration can adapt to substrate and water clarity.

Scale type

none

Mouth position

terminal

Distinctive features

Elongated, cylindrical body, Large, protractile mouth with numerous small, conical teeth, Single, long dorsal fin with a short spinous portion and a much longer soft-rayed portion, Long anal fin, similar in appearance to the soft dorsal fin, Pelvic fins located anterior to the pectoral fins (jugular position), Absence of scales (smooth, slimy skin)

Dorsal fin

Single, long fin extending along most of the back, with 6-10 short, flexible spines followed by 19-23 soft rays.

Tail fin

Rounded to slightly emarginate caudal fin.

Pectoral fin

Large and rounded, positioned laterally.

Distinctive fins

Pelvic fins are jugular (located under the throat), consisting of one spine and five soft rays, often appearing as two separate rays.

Identification Tips

1. 1

   Body Shape and Coloration

   Look for an elongated, cylindrical body with a mottled brown/olive pattern. The absence of scales is a key identifier.

2. 2

   Fin Placement

   Note the single, long dorsal fin and the jugular (throat-positioned) pelvic fins, which appear as two distinct rays.

3. 3

   Mouth

   Observe the large, terminal mouth, indicative of its predatory nature.

4. 4

   Habitat

   If found in a cool, clear, snag-rich freshwater environment in southeastern Australia, it is likely a River Blackfish.

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