How to Identify Stout Whiting

To identify Stout Whiting (Sillago robusta), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Dorsal surface is typically silvery-brown to greenish-brown, fading to silvery-white on the flanks and belly. Often exhibits faint, oblique dark bars or blotches along the upper flanks, which can be more prominent in live specimens. The operculum may have a dark blotch. Fins are generally hyaline (clear) to dusky.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Robust body compared to other whiting species., Relatively large head, approximately 3.0-3.3 times in standard length., Snout length is about 2.5-2.8 times in head length., Lateral line scales typically 68-73., First dorsal fin with 11 spines, second dorsal fin with 1 spine and 18-20 soft rays., Anal fin with 2 spines and 18-20 soft rays., Pectoral fin rays 15-17., Swim bladder with a single posterior extension and two anterior extensions, often with a small, median anterior projection.

Dorsal fin

Two dorsal fins; the first is spiny (XI spines), and the second is soft-rayed (I spine, 18-20 rays). The first dorsal fin is relatively high.

Tail fin

Caudal fin is emarginate (slightly forked) to truncate.

Pectoral fin

Pectoral fins are moderately long, reaching to or slightly beyond the origin of the second dorsal fin.

Distinctive fins

Pelvic fins are thoracic, with one spine and five soft rays.

Identification Tips

1. 1

   Body Shape and Size

   Look for a relatively stout and robust body compared to other whiting species. Adults can reach up to 30 cm (12 inches) in total length, though commonly caught around 20-25 cm.

2. 2

   Head and Snout

   Note the relatively large head and a moderately long snout. The mouth is terminal and slightly oblique.

3. 3

   Coloration

   Observe the silvery-brown to greenish-brown dorsal coloration, fading to white ventrally. Faint, oblique dark bars or blotches on the upper flanks are a key indicator, though they can fade post-mortem.

4. 4

   Fin Ray Counts

   Accurate identification often requires counting fin rays: D1 XI; D2 I, 18-20; A II, 18-20. These counts are crucial for distinguishing it from closely related species.

5. 5

   Swim Bladder Morphology

   For definitive identification, especially in scientific contexts, the morphology of the swim bladder (single posterior extension, two anterior extensions, often a small median anterior projection) is diagnostic.

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