Bluebottle-fish, Nomeus gronovii (Gmelin, 1789)

Scientific name: Nomeus gronovii
Alternative name/s:
Portuguese Man-o-war Fish, Shepherd Fish
A juvenile Bluebottle-fish, Nomeus gronovii Click to enlarge image
A juvenile Bluebottle-fish in a rockpool at a depth of 1 m, Wollongong, New South Wales, April 2007. Image: Sascha Schulz
© Sascha Schulz

Fast Facts

  • Classification
    Genus
    Nomeus
    Species
    gronovii
    Family
    Nomeidae
    Order
    Perciformes
    Class
    Actinopterygii
    Subphylum
    Vertebrata
    Phylum
    Chordata
    Kingdom
    Animalia
  • Size Range
    The species grows to about 26 cm in length.

Introduction

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

Identification

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.

Nomeus dyscritus IA.1928
Nomeus gronovii
Nomeus gronovii

Habitat

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

Distribution

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.

Feeding and diet

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

References

  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.