Humpback Blackdevil, <i>Melanocetus johnsonii</i> Click to enlarge image
A Humpback Blackdevil trawled during the NORFANZ expedition at a depth between the surface and 1200m south-west of Norfolk Island, May 2003 (NMV A25111-006). Image: Kerryn Parkinson
© NORFANZ Founding Parties

Fast Facts

  • Classification
    Species
    johnsonii
    Genus
    Melanocetus
    Family
    Melanocetidae
    Order
    Lophiiformes
    Class
    Actinopterygii
    Subphylum
    Vertebrata
    Phylum
    Chordata
    Kingdom
    Animalia
  • Size Range
    The species is sexually dimorphic. Females grow to 18 cm in length but males only grow to 2.9 cm.

Introduction

Male and female Humpback Blackdevils look very different. Females have a large head and mouth, with long pointed teeth. They grow to 18 cm in length. Males, however, are slender fish that lack a lure and only grow to 2.9 cm.



Identification

The Humpback Blackdevil is a soft-bodied fish that lacks scales and pelvic fins. Females have a large head and mouth, with long pointed teeth. There is a short illicium with a bulbous esca on the snout. Live fish are black.

Two species of Melanocetus occur in Australian waters. The second is Murray's Abyssal Anglerfish, Melanocetus murrayi. Females can be distinguished by the shape of the anterior margin of the vomer (nearly straight in M. johnsonii vs deeply concave in M. murrayi) and size and shape of the escal bulb. Males can be distinguished by the number of denticular teeth on the snout and lower jaw (11 or more and 12 - 24 respectively for M. johnsonii vs 3 - 5 and 10 - 13 for M. murrayi) and the number of dorsal and pectoral fin rays (13 - 15 and 17 - 20 for M. johnsonii vs 12 - 14 and 15 - 18 for M. murrayi).



Distribution

It occurs at mesopelagic depths in tropical and temperate waters worldwide. In Australia it is known from off central to southern New South Wales and near Norfolk Island.

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



References

  1. Bertelsen, E., & Pietsch, T.W. 1983. The Ceratioid Anglerfishes of Australia. Records of the Australian Museum. 35: 77-99.
  2. Pietsch, T. W. 1999. Melanocetidae. in Carpenter, K.E. & V.H. Niem (Eds). FAO Species Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific. Volume 3. Batoid fishes, chimaeras and bony fishes part 1 (Elopidae to Linophrynidae). FAO, Rome. Pp. iii-vi, 1398-2068.
  3. Stewart, A.L. & T.W. Pietsch. 1998. The ceratioid anglerfishes (Lophiiformes: Ceratioidei) of New Zealand. Journal of the Royal Society of New Zealand. 28 (1): 1-37.