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opal fish

Hemerocoetes monopterygius

  • Fish
  • IUCN: Least concern
  • Usual depth7–225 m
  • Water temperature10–19 °C
  • Best monthsMay
  • How commonRare
All species

Photo credit: (c) anonymous, some rights reserved (CC BY-SA) · CC BY-SA · iNaturalist

About this species

The opalfish is a ray-finned fish of the genus Hemerocoetes, found only around New Zealand, at depths of between 5 and 200 metres. Their length is between 10 and 25 centimetres.

Text from the Wikipedia article “Opalfish”, 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: 3 records
  • February: 1 records
  • March: 1 records
  • April: 5 records
  • May: 15 records
  • June: 7 records
  • July: 8 records
  • August: 6 records
  • September: 3 records
  • October: 1 records
  • November: 0 records
  • December: 2 records

Depth and water temperature

Depth

Mostly recorded at 7–225 m · Deepest record: 524 m

  • 0–10 m: 13 records
  • 10–20 m: 19 records
  • 20–30 m: 4 records
  • 30–40 m: 6 records
  • 40–50 m: 2 records
  • 50–60 m: 6 records
  • 60–70 m: 3 records
  • 70–80 m: 0 records
  • 80–90 m: 5 records
  • 90–100 m: 4 records
  • 100–110 m: 1 records
  • 110+ m: 19 records

Water temperature

Recorded in surface water of 10–19 °C

  • 8–10 °C: 1 records
  • 10–12 °C: 13 records
  • 12–14 °C: 15 records
  • 14–16 °C: 23 records
  • 16–18 °C: 30 records
  • 18–20 °C: 3 records

Names and classification

English
opal fish, Opalfish

Other scientific names: Callionymus acanthorhynchus, Callionymus monopterygius, Hemerocoetes acanthorhynchus, Hemerocoetes microps

Similar species

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).
  • 96 open-data records from 1907 to 1993.
  • Species data updated November 3, 2026.

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