How to Identify Hawaiian Stream Goby

To identify Hawaiian Stream Goby (Awaous guamensis), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Variable, typically mottled brown, olive, or gray with irregular dark blotches and saddles along the back and sides, providing excellent camouflage against stream substrates. The ventral surface is usually lighter. Fins are often dusky with faint banding.

Scale type

ctenoid

Mouth position

subterminal

Distinctive features

Large, subterminal mouth with fleshy lips, adapted for scraping algae from rocks., Robust, somewhat cylindrical body., Eyes positioned dorsally on the head., Pelvic fins fused into a single, suction-cup like disc (gobies' characteristic), used for clinging to rocks in strong currents., Presence of small, ctenoid scales on the body, becoming cycloid anteriorly.

Dorsal fin

Two separate dorsal fins; the first with 6 spines, the second with 1 spine and 9-10 soft rays. The first dorsal fin is typically lower than the second.

Tail fin

Rounded to slightly emarginate caudal fin.

Pectoral fin

Large, fan-like pectoral fins with 17-19 rays.

Distinctive fins

Pelvic fins fused into a prominent adhesive disc (frenum present), located anterior to the anus.

Identification Tips

1. 1

   Mouth Shape

   Look for a large, subterminal mouth with thick, fleshy lips, indicative of its grazing diet.

2. 2

   Pelvic Fin Disc

   Observe the fused pelvic fins forming a suction cup on its underside, a key characteristic of gobies that allows them to cling to rocks in strong currents.

3. 3

   Body Coloration and Pattern

   Note the mottled brown/olive/gray coloration with irregular dark blotches, providing camouflage against stream beds.

4. 4

   Dorsal Fins

   Identify the two distinct dorsal fins, with the first being spiny and the second soft-rayed.

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