Flathead flounder

Hippoglossoides dubius

Fish
IUCN: Least concern

Usual depth67–466 m
Water temperature5–19 °C
Best monthsJuly and September
How commonRare

About this species

The flathead flounder is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on bottoms in shallow coastal waters, at depths of between 10 and 600 metres. Its native habitat is the northwestern Pacific, particularly the seas of Japan and Okhotsk, and the coastlines of Kamchatka and Korea. It grows up to 45 centimetres (18 in) in length.

Text from the Wikipedia article “Flathead flounder”, 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: 0 records
March: 0 records
April: 3 records
May: 1 records
June: 2 records
July: 9 records
August: 0 records
September: 14 records
October: 7 records
November: 0 records
December: 1 records

Depth and water temperature

Depth

Mostly recorded at 67–466 m · Deepest record: 1,998 m

30–40 m: 1 records
40–50 m: 0 records
50–60 m: 2 records
60–70 m: 1 records
70–80 m: 4 records
80–90 m: 0 records
90–100 m: 0 records
100–110 m: 0 records
110–120 m: 2 records
120–130 m: 0 records
130–140 m: 0 records
140+ m: 25 records

Water temperature

Recorded in surface water of 5–19 °C

4–6 °C: 1 records
6–8 °C: 7 records
8–10 °C: 2 records
10–12 °C: 3 records
12–14 °C: 3 records
14–16 °C: 5 records
16–18 °C: 4 records
18–20 °C: 11 records

Names and classification

English: Flathead flounder, akagarei

Names in 4 more languages

French: Balai japonais
Japanese: Aka-garei, Akagarei, アカガレイ
Korean: 홍가자미
Simplified Chinese: 犬形擬庸鰈

Other scientific names: Hippoglossoides katakurae

Similar species

Kamchatka flounder
Atheresthes evermanni
Korean flounder
Glyptocephalus stelleri
Roughscale sole
Clidoderma asperrimum
Shotted halibut
Eopsetta grigorjewi
Slime flounder
Microstomus achne
Pointhead flounder
Cleisthenes pinetorum

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).
47 open-data records from 1906 to 2009.
Species data updated November 3, 2026.

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