Medusafish

About this species

Icichthys lockingtoni, commonly known as the medusafish, is a species of centrolophid ray-finned fish native to the northern Pacific Ocean, where it ranges from Japan and the Gulf of Alaska to central Baja California in Mexico. It typically occurs at a depth of 0 to 91 m, although it has been reported from as deep as 900 m (2953 ft). Young individuals of the species are abundant offshore, often in association with jellyfish in a symbiotic relationship that is likely commensal. The species reaches 46 cm in total length.

Text from the Wikipedia article “Icichthys lockingtoni”, 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: 316 records
February: 339 records
March: 261 records
April: 513 records
May: 588 records
June: 424 records
July: 414 records
August: 128 records
September: 25 records
October: 85 records
November: 187 records
December: 41 records

Depth and water temperature

Depth

Mostly recorded at 0–28 m · Deepest record: 1,500.8 m

0–10 m: 625 records
10–20 m: 8 records
20–30 m: 183 records
30–40 m: 1 records
40–50 m: 2 records
50–60 m: 0 records
60–70 m: 0 records
70–80 m: 0 records
80–90 m: 0 records
90–100 m: 0 records
100–110 m: 2 records
110+ m: 24 records

Water temperature

Recorded in surface water of 5–18 °C

4–6 °C: 4 records
6–8 °C: 3 records
8–10 °C: 0 records
10–12 °C: 70 records
12–14 °C: 254 records
14–16 °C: 317 records
16–18 °C: 150 records
18–20 °C: 5 records

Photos

(c) Ryan Donnelly, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Aiva Noringseth, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Sean Vanderluit, some rights reserved (CC BY) · CC BY · iNaturalist
(c) Sean Vanderluit, some rights reserved (CC BY) · CC BY · iNaturalist

Names and classification

English: Medusafish, brown rudderfish, medusafish

Names in 3 more languages

Spanish: cojinoba medusa
French: stromatée-médusae, stromatée-méduse
Japanese: Kuromedai, クロメダイ

Similar species

Southern driftfish
Icichthys australis
Black fish
Centrolophus niger
Antarctic butterfish
Hyperoglyphe antarctica
Japanese butterfish
Hyperoglyphe japonica
Barrelfish
Hyperoglyphe perciformis

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).
3,517 open-data records from 1904 to 2023.
Species data updated November 3, 2026.