Animal Species:Bluebottle-fish, Nomeus gronovii (Gmelin, 1789)

Young Bluebottle-fish are pelagic, but adults are demersal. The juveniles live among the tentacles of the blue bottle, Physalia,

Standard Common Name


Alternative Name/s

Portuguese Man-o-war Fish, Shepherd Fish


The Bluebottle-fish has a compressed body and a large forked caudal fin. The pelvic fins are large and fan-like.

Juveniles are bright blue on the back and silver on the sides. There are blue spots and blotches on the body and fins. Adults are usually dark brown.

Nomeus gronovii is only species in the genus Nomeus.

Size range

The species grows to about 26 cm in length.


It occurs in tropical and some temperate continental shelf waters circumglobally.

In Australia, the Bluebottle-fish is known from the offshore islands of north-western Western Australia, around the tropical north of the country and down the east coast to Bass Strait, Victoria. It has also been recorded from Lord Howe Island.

The map below shows the Australian distribution of the species based on public sightings and specimens in Australian Museums. Click on the map for detailed information.  Source: Atlas of Living Australia.

Nomeus gronovii

Distribution by collection data

Ozcam map of Bluebottle-fish specimens in the Australian Museum.

What does this mean?


Young Bluebottle-fish are pelagic, but adults are demersal. The juveniles live among the tentacles of the blue bottle, Physalia.

Feeding and Diet

Juveniles are believed to eat small pelagic invertebrates and may nibble on the blue bottle’s tentacles.



What does this mean?


  1. Hoese, D.F., Bray, D.J., Paxton, J.R. & G.R. Allen. 2006. Fishes. in Beesley, P.L. & A. Wells. (eds) Zoological Catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia. parts 1-3, pages 1-2178.
  2. McDowall, R.M. Family Nomeidae. in Gomon, M.F., Glover, C.J.M. & R.H. Kuiter (Eds). 1994. The Fishes of Australia's South Coast. State Print, Adelaide. Pp. 992.
  3. Kuiter, R.H. 2000. Coastal Fishes of South-eastern Australia. Gary Allen. Pp. 437.

Mark McGrouther , Collection Manager, Ichthyology
Last Updated:

Tags fishes, ichthyology, Bluebottle-fish, Nomeus gronovii, Nomeidae, blue, purple, silver, black, 'normal fish', 10 cm - 30 cm, blotches/mottled, countershaded, pelagic, marine, juvenile/young, adult, fan-like fins,


Mark McGrouther - 8.09 AM, 28 September 2009
Thanks Sascha, The registration number of the fish is AMS I.44072-001. I'll also add the rego number to the two image captions.
Sascha Schulz - 11.09 AM, 25 September 2009
The Bluebottle-fish pictured was captured and kept in an aquarium for 2 days, after it which developed swimming problems and died. It was in poor condition to begin with. The rockpool it was found in also contained numerous bluebottles, as well as other Bluebottle-fish. Some rough research revealed that this species has not been kept in aquaria succesfully. It is presumed to feed on the gonad tissue of the bluebottle. From (rather hazardous) personal observation of this species in the wild, it appears to be immune to the bluebottle toxins. The pictured fish is now registered in the AMS collection. Mark: If you could put up the rego number? :-)

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