Black gemfish

Nesiarchus nasutus

Fish
IUCN: Least concern

Usual depth60–1,197 m
Water temperature9–30 °C
Best monthsJune and September
How commonOccasional

About this species

Nesiarchus nasutus, the black gemfish or violet snake mackerel, is a species of snake mackerel found in tropical and subtropical waters in most parts of the world, though not in east Pacific and north Indian waters. It occurs at depths of from 200 to 1,200 metres though they make diel vertical migrations from benthopelagic to mesopelagic depths at night. This species can reach a length of 130 centimetres (51 in) SL though most do not exceed 80 centimetres (31 in) SL. It is of minor importance to local commercial fisheries. This species is currently the only known member of its genus, Nesiarchus.

Text from the Wikipedia article “Nesiarchus nasutus”, 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: 0 records
February: 6 records
March: 5 records
April: 5 records
May: 18 records
June: 21 records
July: 12 records
August: 16 records
September: 34 records
October: 11 records
November: 10 records
December: 5 records

Depth and water temperature

Depth

Mostly recorded at 60–1,197 m · Deepest record: 2,160.5 m

0–10 m: 5 records
10–20 m: 1 records
20–30 m: 3 records
30–40 m: 0 records
40–50 m: 2 records
50–60 m: 2 records
60–70 m: 4 records
70–80 m: 0 records
80–90 m: 1 records
90–100 m: 1 records
100–110 m: 1 records
110+ m: 114 records

Water temperature

Recorded in surface water of 9–30 °C

8–10 °C: 1 records
10–12 °C: 2 records
12–14 °C: 22 records
14–16 °C: 14 records
16–18 °C: 11 records
18–20 °C: 14 records
20–22 °C: 18 records
22–24 °C: 27 records
24–26 °C: 9 records
26–28 °C: 38 records
28–30 °C: 25 records

Names and classification

English: Black gemfish, Johnson's scabbardfish, Scabbardfish, Black Barracouta, black gemfish, Black gemfish, Johnson's Scabbardfish, scabbardfish, violet snake mackerel

Names in 3 more languages

Spanish: dómine narizón, escolar narigudo, Escolar narigudo, Pez Espada Picudo
French: Dómine Narizón, Escolier long nez
Japanese: Hashinagakurotachi, ハシナガクロタチ

Other scientific names: Bipinnula violacea, Escolar violaceus, Prometheus paradoxus, Thyrsitops violaceus

Similar species

Snake mackerel
Gempylus serpens
Roudi escolar
Promethichthys prometheus
Striped escolar
Diplospinus multistriatus
Black snake mackerel
Nealotus tripes
Slender escolar
Paradiplospinus gracilis
Royal escolar
Rexea prometheoides

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).
439 open-data records from 1921 to 2023.
Species data updated November 5, 2026.

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