How to Identify Cobalt Goby

To identify Cobalt Goby (Stiphodon semoni), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Males exhibit striking iridescent blue to cobalt blue coloration, particularly during breeding, with a darker dorsal stripe and sometimes yellow or orange fins. Females are typically more subdued, often brownish-grey with darker blotches or stripes, and may have a yellowish tint to their fins. Both sexes have a series of small, dark spots along the lateral line.

Scale type

ctenoid

Mouth position

inferior

Distinctive features

Specialized ventral fins fused into a suction cup-like disc, used for clinging to rocks in fast currents., Inferior mouth with numerous small, comb-like teeth adapted for scraping algae., Sexual dimorphism in coloration, especially pronounced in breeding males.

Dorsal fin

Two separate dorsal fins. The first dorsal fin has 6-7 spines, and the second dorsal fin has 1 spine and 9-10 soft rays. The first dorsal fin in males can be elongated and more colorful.

Tail fin

Caudal fin is truncate to slightly rounded.

Pectoral fin

Pectoral fins are broad and fan-like, aiding in stability in currents.

Distinctive fins

Pelvic fins are fused into a prominent adhesive disc, characteristic of gobies in the family Gobiidae, particularly rheophilic species.

Identification Tips

1. 1

   Coloration (Males)

   Vibrant iridescent blue body, often with a darker dorsal stripe. This is the most striking feature for identification.

2. 2

   Coloration (Females)

   More subdued brownish-grey with darker blotches or stripes, sometimes with yellowish fins.

3. 3

   Mouth Structure

   Inferior mouth with comb-like teeth, visible upon close inspection, indicating its herbivorous diet.

4. 4

   Pelvic Fin Disc

   Fused pelvic fins forming a suction cup, a key characteristic of Stiphodon species, used for adhesion to substrates in strong currents.

5. 5

   Habitat Preference

   Presence in fast-flowing, clear, rocky streams is a strong indicator.

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