Sicyopterus stimpsoni (Gill, 1860)
Stimpson's goby
Sicyopterus stimpsoni
photo by Awai, M.

Family:  Gobiidae (Gobies), subfamily: Sicydiinae
Max. size:  19.8 cm SL (male/unsexed)
Environment:  demersal; freshwater; brackish; marine; depth range 1 - 300 m, amphidromous
Distribution:  Oceania: found in larger Hawaiian Islands and Society Islands.
Diagnosis:  Mature males characterized by an extended ray on the first dorsal fin which is very long and overlaps the second dorsal fin when folded; courting male can appear turquoise to nearly black, with two "racing" stripes along the length of the body; females and juveniles normally mottled brown to gray-green; both sexes turn black when disturbed (Ref. 44091).
Biology:  Benthic in lower and middle reaches of streams (Ref. 58302). Adults inhabit mountainous streams. Are well adapted to exist in swiftly-flowing basalt-bottomed stream habitat (Ref. 26461). Presence of these species signify water of good water quality (Ref. 44091). Adults are primarily herbivorous, scraping algae off rocks, while the larvae are omnivorous; occasionally caught with nets ('upena), usually after being stupefied with native plants (e.g. hola and ahuhu), a process requiring partial diversion of the stream to reduce water flow; particularly prized in July and August when the females are gravid (Ref. 44091).
IUCN Red List Status: Lower Risk: near threatened (LR/nt); Date assessed: 01 August 1996 Ref. (130435)
Threat to humans:  harmless


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