Estuarine Threefin

About this species

Forsterygion gymnotum, commonly known as the robust triplefin, Tasmanian robust triplefin, bare-backed triplefin, multifid-tentacled robust triplefin, and the estuarine threefin in Australia is a type of triplefin fish belonging to the genus Forsterygion. It is one of twenty-seven triplefin species native to New Zealand but was first described in Tasmania in 1977 by Eric Oswald Scott.

Text from the Wikipedia article “Tasmanian robust triplefin”, licensed CC BY-SA 4.0. Read the article

Where and when

Where it has been recorded

Worldwide

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Best months

Worldwide (open data)

January: 7 records
February: 16 records
March: 17 records
April: 14 records
May: 12 records
June: 16 records
July: 4 records
August: 13 records
September: 8 records
October: 7 records
November: 10 records
December: 7 records

Depth and water temperature

Depth

Mostly recorded at 1–6 m · Deepest record: 14.5 m

0–10 m: 19 records
10–20 m: 2 records

Water temperature

Recorded in surface water of 14–18 °C

12–14 °C: 11 records
14–16 °C: 13 records
16–18 °C: 7 records

Photos

(c) Jon Sullivan, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Kelvin Perrie, some rights reserved (CC BY) · CC BY · iNaturalist
(c) John Barkla, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Kelvin Perrie, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Sebastian Doak, some rights reserved (CC BY) · CC BY · iNaturalist
(c) henry_id, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Sebastian Doak, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: Estuarine Threefin, Mimic Robust Triplefin, Multifid-tentacled Robust Triplefin, Robust Triplefin

Other scientific names: Forsterygion gymnota, Grahamina gymnota, Grahamina signata

Similar species

Common Threefin
Forsterygion lapillum
Banded triplefin
Forsterygion malcolmi
Oblique-swimming Triplefin
Forsterygion maryannae
Many-rayed Threefin
Forsterygion varium
Mottled triplefin
Forsterygion capito
Yellow-and-black Triplefin
Forsterygion flavonigrum

Sources and credits

Names and taxonomy: WoRMS (CC BY 4.0) and the GBIF Backbone (CC BY 4.0). Photos: iNaturalist observers, each under the licence shown (CC0, CC BY or CC BY-SA).

Depth, temperature, months and maps: records from OBIS and GBIF under CC0 or CC BY.
Descriptions: Wikipedia, licensed CC BY-SA, each linked to its article.
Conservation status as published by GBIF (IUCN Red List).
125 open-data records from 1950 to 2020.
Species data updated November 2, 2026.