How to Identify Biawak River Goby

To identify Biawak River Goby (Gobiopterus brachypterus), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Generally translucent to pale yellowish-brown, often with faint, irregular darker markings or speckles along the flanks. The fins are typically hyaline (clear) or slightly dusky. Some individuals may exhibit a silvery sheen.

Scale type

ctenoid

Mouth position

superior

Distinctive features

Small adult size, typically reaching 2-3 cm (0.8-1.2 inches) standard length., Relatively short dorsal and anal fins, giving rise to its specific epithet 'brachypterus' (short-finned)., Two separate dorsal fins; the first dorsal fin has 6-7 spines, and the second dorsal fin has 1 spine and 6-7 soft rays., Anal fin with 1 spine and 6-7 soft rays., Pectoral fins are relatively large and fan-like., Pelvic fins are fused into a disc-like structure, characteristic of gobies, used for adhesion to substrates., Absence of scales on the head and nape, with scales present only on the posterior part of the body.

Dorsal fin

Two separate dorsal fins. First dorsal fin with VI-VII spines. Second dorsal fin with I spine and 6-7 soft rays.

Tail fin

Rounded to slightly emarginate caudal fin.

Pectoral fin

Large, fan-like pectoral fins with 14-16 rays.

Distinctive fins

Pelvic fins fused into a prominent adhesive disc.

Identification Tips

1. 1

   Size and Body Shape

   Look for a very small, slender, and somewhat elongated goby, typically under 3 cm in length.

2. 2

   Fin Length

   Observe the dorsal and anal fins; they are noticeably shorter compared to many other goby species, a key diagnostic feature.

3. 3

   Coloration

   Note the translucent to pale body coloration, often with subtle markings, which helps it blend into its environment.

4. 4

   Pelvic Fin Disc

   Confirm the presence of a fused, disc-like pelvic fin, characteristic of gobies, used for clinging to surfaces.

5. 5

   Scalation

   Examine the scalation pattern; scales are absent on the head and anterior body, present only on the posterior half.

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