Olive Green Triplefin, Enneapterygius olivaceus Dewa, Tashiro & Motomura 2023

Summary:

A triplefin with black pectoral fins in nuptial males.

Cite this page as:

Bray, D.J. 2025, Enneapterygius olivaceus in Fishes of Australia, accessed 27 Jun 2025, https://fishesofaustralia.net.au/Home/species/5766

Olive Green Triplefin, Enneapterygius olivaceus Dewa, Tashiro & Motomura 2023

More Info

Distribution	Lizard Island, Great Barrier Reef, Queensland. Elsewhere the species is known from Japan (Ryukyu Islands), the Philippines & Vanuatu.
Features	Dorsal fin III, XI-XIII, 8-10; Anal fin I, 16-17; Scale rows in longitudinal series 29-32; Notched lateral-line scales 18-22, pored lateral-line scales 12-14. 2-3 scales below the first notched lateral-line scale; a single symphyseal mandibular-pore (mandibular pore formula 3 + 1 + 3), no distinct line on the anal-fin membranes.
Colour	Fresh coloration: Males - body generally olive green; scattered brownish-orange pigmentation particularly along scale margins; small indistinct white spots aligned horizontally on level of notched scale series. Head, including eye, snout, lips, cheek, and opercle, and pectoral-fin base dense black [dark grey with scattered melanophores]. Pre-pelvic region and underside of abdomen greyish. Orbital tentacle and iris brownish-orange, pupil black. Caudal-fin base with narrow whitish vertical bar. First dorsal fin black, with brownish-orange pigmentation between 1st and 2nd spine membranes. Second and third dorsal fins generally transparent, with two black longitudinal bands on fin margin and base, width of former ca. 1/2 length of spines, latter somewhat indistinct. Pectoral fin transparent, membranes between lower 6–8 rays black [translucent dark grey]. Pelvic fins black with white edges. Anal fin generally black, with translucent margin [translucent greyish with scattered white spots]; fin ray bases with 7 or 8 white spots aligned along lower margin of posterior body. Caudal fin semi-transparent, white with greyish rays and ca. 5 faint whitish bars. Females - Body generally yellowish-white; scattered brownish-orange pigmentation particularly along scale margins, darker on lateral surface forming indistinct A-shaped or X-shaped bars; ca. 5 white spots, width subequal to pupil diameter, aligned horizontally on level of notched scale series. Cheek and opercle reddish-brown. flecked with golden blotch; reddish-brown stripes extending from tip of snout to anterior margin of eye, its width subequal to upper lip width. Pre-pelvic region and underside of abdomen whitish. Orbital tentacle and iris brownish-orange; pupil black margined with orange. Lower margin of posterior body with ca. 9 or 10 brownish-red spots aligned along anal-fin base. Caudal-fin base with narrow yellowish-white vertical bands. First dorsal fin transparent with scattered melanophores; brownish-orange or cream pigmentation between 1st and 2rd spine membranes. Second and third dorsal fins generally transparent, with 2 or 3 yellowish oblique bands irregularly; faint greyish longitudinal bands on fin margin and edge. Anal fin with greyish pigmentation on central region of fin rays; yellowish irregular blotches forming ca. 7 or 8 oblique bars on fin membranes. Pectoral fin translucent white, with yellowish blotches; fin rays flecked with broad brown pigmentation forming ca. 4 or 5 vertical bands on pectoral fin. Pelvic fins translucent white. Caudal fin translucent white with narrow yellowish vertical bars; fin rays dark brown. Coloration of the pale male is very similar.
Similar Species	Enneapterygius olivaceus differs from the similar Yellow-back Threefin, E. gracilis, in having slightly fewer notched lateral-line scales [18–22 (modally 20) in the former vs. 19–21 (21) in the latter] and scales below the 1st notched scale [2 or 3 (modally 2) vs. 3–3.5], a single symphyseal mandibular-pore (mandibular pore formula: 3 + 1 + 3) (vs. double symphyseal mandibular-pores, 3 + 2 + 3), black pectoral fins in nuptial males (vs. pectoral fin pale with brownish blotches in both sexes), and no distinct lines on the anal-fin membranes (vs. anal fin with 7–9 brownish oblique bands).
Etymology	The specific name is from the Latin olivaceus (= olive-coloured), in reference to the olivaceous body colour of specimens.
Species Citation	Enneapterygius olivaceus Dewa, Tashiro & Motomura 2023, Zootaxa 5374(3): 334, Figs. 1-3, 5a. Type locality: Off Shinaha Beach, Chabana, Yoron-jima Island, Amami Islands, Japan, 27°24'36"N, 128°24'57"E, depth 1-1.8 m.
Author	Bray, D.J. 2025
Resources	Atlas of Living Australia Australian Faunal Directory Catalog of Fishes

Olive Green Triplefin, Enneapterygius olivaceus Dewa, Tashiro & Motomura 2023

References

Dewa, Y. & Motomura, H. 2024. First records of two triplefins, Enneapterygius rhothion and Enneapterygius olivaceus (Actinopterygii: Blenniiformes: Tripterygiidae), from Australia and Vanuatu. Acta Ichthyologica et Piscatoria 54: 261-268. https://doi.org/10.3897/aiep.54.135448

Dewa, Y., Tashiro, S. & Motomura, H. 2023. A new species of the genus Enneapterygius (Perciformes: Tripterygiidae) from Japan and the Philippines, with a synopsis and synonymy of related species. Zootaxa 5374(3): 333-360. https://doi.org/10.11646/zootaxa.5374.3.2

Williams, J.T. 2025. Enneapterygius olivaceus. The IUCN Red List of Threatened Species 2025: e.T252732614A252734722. Accessed on 17 June 2025.