Hypnos monopterygius

Coffin Ray | Cramp-fish | Electric Ray | Numbfish | Numbie | Short-tail Electric Ray
Hypnos monopterygius
Hypnos monopterygius, Jervis Bay, NSW, Photo: Andrew Green
Hypnos monopterygius
Hypnos monopterygius, Port Stephens, New South Wales, Australia, Photo: Tom Davis
Hypnos monopterygius
Hypnos monopterygius, NSW, Australia, Photo: Ian Shaw
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Hypnos monopterygius
Hypnos monopterygius
Hypnos monopterygius


Temperate Australasia, Tropical Indo-Pacific


Double-lobed body, 2 rounded dorsal fins and tail, and small eyes set close together near midline. Delivers a powerful electric shock if touched, which stuns fish prey and incautious divers.


Max Size: 70 cm

Sea Temperature Range: 15.4-25.2°C

Depth: 0-220m

Habitat Generalization Index: N/A

Also referred to as the SGI (Species Generalisation Index), this describes the habitat niche breadth of the species. Species with values less than 15 are found in a relatively narrow range of reef habitat types (specialists), while those over 25 may be found on most hard substrates within their range (generalists). Learn more here.

Conservation and Rarity

IUCN Status: Least Concern

Occurrence: Infrequent (5.6% of sites)

Occurrence describes how often the species is found on surveys within its distribution. It is calculated as the % of reef sites surveyed by RLS divers across all the ecoregions in which the species has been observed

Abundance: Solitary (1 per transect)

Abundance is calculated as the average number of individuals recorded per RLS transect, where present.

Edit by: extract from RD Stuart-Smith, GJ Edgar, AJ Green, IV Shaw. 2015. Tropical Marine Fishes of Australia. Reed New Holland