How to Identify Brook Silverside

To identify Brook Silverside (Labidesthes sicculus), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Translucent, often with a greenish-yellow tint dorsally and silvery-white ventrally. A prominent, iridescent silver stripe extends from the operculum to the caudal fin base. The dorsal surface may have fine melanophores.

Scale type

cycloid

Mouth position

superior

Distinctive features

Extremely slender and elongated body, almost needle-like., Large, upward-pointing mouth (superior mouth)., Two widely separated dorsal fins., Prominent silver lateral stripe., Absence of a lateral line canal on the body, though a lateral stripe is present.

Dorsal fin

Two dorsal fins; the first is small with 4-6 weak spines, located far back on the body. The second dorsal fin is soft-rayed (9-12 rays) and positioned directly above the anal fin.

Tail fin

Moderately forked caudal fin.

Pectoral fin

Small, high-set pectoral fins (11-14 rays).

Distinctive fins

Anal fin is long with 20-26 rays, originating anterior to the second dorsal fin. Pelvic fins are small and abdominal.

Identification Tips

1. 1

   Body Shape and Coloration

   Look for a very slender, translucent body with a distinct, iridescent silver stripe running along the sides. The overall appearance is delicate and glass-like.

2. 2

   Mouth Position

   The mouth is distinctly upturned (superior), indicating its surface-feeding habit. The lower jaw protrudes beyond the upper jaw.

3. 3

   Dorsal Fins

   Note the two widely separated dorsal fins. The first dorsal fin is small and spiny, located far back on the body, almost directly above the anal fin origin.

4. 4

   Size

   Adults typically range from 7-13 cm (2.8-5.1 inches) in total length, rarely exceeding 15 cm.

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