Commerson’s Freshwater Goby

Large head. Fusiform body. Large and terminal mouth. Two dorsal fins. First with 6 spines, second with 1 spine and 10 to 11 branched rays. Adults body and fins usually grey to black with a clearer belly. Juveniles brown with a serie of darker rounded marks along the flanks. First dorsal usually shows a black mark in its posterior part, especially for young specimens. Fading while fish age. 10 to 25cm (Ref. 57749).

Amphidromous. Refers to fishes that regularly migrate between freshwater and the sea (in both directions), but not for the purpose of breeding, as in anadromous and catadromous species. Sub-division of diadromous. Migrations should be cyclical and predictable and cover more than 100 km.Characteristic elements in amphidromy are: reproduction in fresh water, passage to sea by newly hatched larvae, a period of feeding and growing at sea usually a few months long, return to fresh water of well-grown juveniles, a further period of feeding and growing in fresh water, followed by reproduction there (Ref. 82692).

Dorsal spines (total): 7; Dorsal soft rays (total): 10 - 11; Analspines: 1; Analsoft rays: 9 - 10

This species occurs in freshwaters and sometimes brackish waters in slow to fast current waters to the base of the first falls. Usually occurs in clear waters with sand, gravel or rock bottom. Feeds on algae, detritus, worms, gastropods and crustaceans. Close biology to A. guamensis. Amphidromous species. Adults migrate to the mouth of the rivers for reproduction. Females spawn on the rocks' surface where the males fecund the eggs. Males protect the eggs until they hatch (incubation lasts 24 to 70hrs). Larvae, translucid, are then carried into estuaries or sea. They come back after they spent 150 to 165 days in seawaters (Ref. 57749). Also Ref. 4343.

Awaous commersoni, or Commerson's freshwater goby, is a species of goby found on islands in the Southwest Indian Ocean.