Birdwire Rockcod, Epinephelus merra Bloch 1793

Other Names: Black-spotted Rock-cod, Common Birdwire Rockcod, Dwarf Spotted Rockcod, Dwarf Spotter Grouper, Dwarf-spotted Grouper, Honeycomb Cod, Honeycomb Grouper, Honeycomb Rock Cod, Honeycomb Rock-cod, Wire-netted Reefcod, Wire-netting Cod, Wire-netting Rock-cod

A Birdwire Rockcod, Epinephelus merra, on the Great Barrier Reef, Queensland, June 2009. Source: Graham Edgar / Reef Life Survey. License: CC by Attribution

A small rockcod covered in close-spaced brown blotches (more widely spaced on the belly), forming a honeycomb pattern, and sometimes indistinct dark vertical bands.

Cite this page as:
Bray, D.J., Epinephelus merra in Fishes of Australia, accessed 24 Jun 2024,

Birdwire Rockcod, Epinephelus merra Bloch 1793

More Info


Ashmore Reef, Timor Sea, Rowley Shoals and Scott Reef, and Exmouth, Western Australia, to Botany Bay, New South Wales, reefs in the Coral Sea; also Cocos (Keeling) Islands and Christmas Island, and the Lord Howe Island region, in the Tasman Sea. Elsewhere, the species is widespread and common in the tropical, Indo-west-central Pacific.
Commonly inhabits shallow lagoons and semi-protected seaward reefs; juveniles shelter in staghorn Acropora coral thickets. The species is site attached, and individuals remain in the same area throughout their life.


Dorsal fin XI, 15-17; Anal fin III, 8. 
Scales ctenoid on body except cycloid anteriorly above lateral line, on thorax and lower abdomen; body with auxiliary scales; ; pelvic fins, 1.7-2.2 in head length; head length 2.3-2.6 times in SL; greatest depth of body 2.8-3.3 in SL; interorbital area flat, dorsal head profile convex; rounded or subangular preopercle, serrae at angle enlarged; almost straight upper edge of operculum; subequal anterior and posterior nostrils or posterior nostrils larger; maxilla reaches past vertical at rear edge of eye; 2-4 rows of teeth on midlateral part of lower jaw, inner teeth about twice length of outer teeth; rounded caudal fin; pyloric caeca 8.


Body with a hexagon or honeycomb pattern, sometimes coalescing into short rows of about five darker diagonal bands, each two to five hexagons wide.


Carnivore - ambush predator, feeds on crustaceans and small fishes when young, increasingly consuming fishes with growth.


A monandric protogynous hermaphrodite - starts life as a female, changing sex to male at 3-5 years of age. Spawning occurs shortly after the full moon during summer. 


Fishes commercially and recreationally, and also taken in artisanal fisheries in some parts of its distribution range.

Similar Species

Frequently confused with Epinephelus quoyanus.

Species Citation

Epinephelus merra Bloch 1793, Naturgeschichte der ausl√§ndischen Fische 7: 17, pl. 329. Type locality: Japan. 


Bray, D.J.


Australian Faunal Directory

Birdwire Rockcod, Epinephelus merra Bloch 1793


Alan, M.A. & Nakamura, M. (2007). Efferent duct differentiation during female-to-male sex change in honeycomb grouper Epinephelus merra. Journal of Fish Biology 71: 1192-1202. 

Allen, G.R. 1997. Marine Fishes of Tropical Australia and South-east Asia. Perth : Western Australian Museum 292 pp. 106 pls. 

Allen, G.R. & Erdmann, M.V. 2012. Reef fishes of the East Indies. Perth : Tropical Reef Research 3 vols, 1260 pp.

Allen, G.R., Hoese, D.F., Paxton, J.R., Randall, J.E., Russell, B.C., Starck, W.A., Talbot, F.H. & Whitley, G.P. 1976. Annotated checklist of the fishes of Lord Howe Island. Records of the Australian Museum 30(15): 365-454 figs 1-2 

Allen, G.R. & Smith-Vaniz, W.F. 1994. Fishes of Cocos (Keeling) Islands. Atoll Research Bulletin 412: 1-21.

Allen, G.R., Steene, R.C. & Orchard, M. 2007. Fishes of Christmas Island. Christmas Island : Christmas Island Natural History Association 2 edn, 284 pp. 

Allen, G.R. & Swainston, R. 1988. The Marine Fishes of North-Western Australia. A field guide for anglers and divers. Perth, WA : Western Australian Museum vi 201 pp., 70 pls. 

Beukers-Stewart, B.D. & Jones, G.P. 2004. The influence of prey abundance on the feeding ecology of two piscivorous species of coral reef fish, Journal of Experimental Marine Biology and Ecology 299: 155-184.

Bloch, M.E. 1793. Naturgeschichte der ausl√§ndischen Fische. Berlin : J. Morino Vol. 7 144 pp. pls 324-360. 

Choat, J.H., van Herwerden, L., Robbins, W.D., Hobbs, J.P. & Ayling, A.M. 2006. A report on the ecological surveys undertaken at Middleton and Elizabeth Reefs, February 2006. Report by James Cook University to the Department of the Environment and Heritage. 65 pp. 

Craig, M.T., Sadovy de Mitcheson, Y.J. & Heemstra, P.C. 2011. Groupers of the World: a Field and Market Guide. Grahamstown, South Africa : NISC Ltd 356 pp., Appendix 47 pp.

Francis, M. 1993. Checklist of the coastal fishes of Lord Howe, Norfolk, and Kermadec Islands, southwest Pacific Ocean. Pacific Science 47(2): 136-170 figs 1-2 

Gill, A.C. & Reader, S.E. 1992. Fishes. pp. 90-93, 193-228 in Hutchings, P. (ed.) Reef Biology. A Survey of Elizabeth and Middleton Reefs, South Pacific. Canberra : Australian National Parks Vol. 3, Kowari 230 pp. 

Heemstra, P.C. & Randall, J.E. 1993. Groupers of the World (Family Serranidae, Subfamily Epinephelinae). An annotated and illustrated catalogue of grouper, rockcod, hind, coral grouper and lyretail species known to date. FAO Fisheries Synopsis No. 125 Vol. 16. Rome: FAO. pp. 1-382.

Heemstra, P.C. & Randall, J.E. 1999. Family Serranidae. pp. 2442-2548 in Carpenter, K.E. & Niem, T.H. (eds) The Living Marine Resources of the Western Central Pacific. FAO Species Identification Guide for Fisheries Purposes. Rome : FAO Vol. 4 pp. 2069-2790.

Hutchins, J.B. 2001. Biodiversity of shallow reef fish assemblages in Western Australia using a rapid censusing technique. Records of the Western Australian Museum 20: 247-270.

Jagadis, I., B. Ignatius, D. Kandasamiw & M.D. Ajmal Khan. 2006. Embryonic and larval development of honeycomb grouper Epinephelus merra Bloch, Aquaculture Research 37: 1140-1145.

Johannes, R.E. and J.W. MacFarlane, 1991. Traditional fishing in the Torres Strait Islands. CSIRO Division of Fisheries, Tasmania, Australia. 268 pp.

Johnson, J.W. 1999. Annotated checklist of the fishes of Moreton Bay, Queensland, Australia. Memoirs of the Queensland Museum 43(2): 709-762.

Kuiter, R.H. 1992. Tropical Reef-Fishes of the Western Pacific, Indonesia and Adjacent Waters. Jakarta : PT Gramedia Pustaka Utama 314 pp. pls. 

Kuiter, R.H. 1993. Coastal Fishes of South-eastern Australia. Bathurst : Crawford House Press 437 pp.

Lee, Y.D., Park, S.H., Takemura, A. & Takano, K. 2002.  Histological observations of seasonal reproductive and lunar-related spawning cycles in the female honeycomb grouper Epinephelus merra in Okinawan waters. Fisheries Science 68(4): 872-877.

Liu, M. & Yeeting, B. 2008. Epinephelus merra. The IUCN Red List of Threatened Species 2008: e.T132788A3451752. Downloaded on 07 December 2016.

Pothin, K., Letourneur, Y. & Lecompte-Finiger, R. 2004. Age, growth and mortality of the tropical grouper Epinephelus merra (Pisces: Serranidae) on Reunion Island, SW Indian Ocean. Vie et Milieu 54(4): 193-202.

Randall, J.E. 2005. Reef and shore fishes of the South Pacific. New Caledonia to Tahiti and the Pitcairn Islands. Honolulu : University of Hawaii Press 707 pp.

Randall, J.E., Allen, G.R. & Steene, R. 1990. Fishes of the Great Barrier Reef and Coral Sea. Bathurst : Crawford House Press 507 pp. figs. 

Randall, J.E., Allen, G.R. & Steene, R. 1997. Fishes of the Great Barrier Reef and Coral Sea. Bathurst : Crawford House Press 557 pp. figs. 

Randall, J.E. & Heemstra, P.C. 1991. Revision of Indo-Pacific groupers (Perciformes: Serranidae: Epinephelinae), with descriptions of five new species. Indo-Pacific Fishes 20: 1-332.

Sazaki, J., Teruya, K. & Ueno, S. 1999. Embryonic, larval and juvenile deveopment of the grouper Epinephelus merra (Teleostei: Serranidae). Tokai Daigaku Kaiyo Jo Kenkyu Ho Koku 20: 147-155. 

Shapiro, D.Y. 1987. Reproduction in groupers, pp. 295-327. In: J.J. Polovina & S. Ralston (eds), Tropical Snappers and Groupers. Biology and Fisheries Management,  Westview Press, Boulder, USA and London, UK. 

Song, Y.B., Park, Y.J., Takemura, K., Kim, H.J., Choi, M.S., Choi, Y.C. & Lee, Y.D. 2003. Histological observations of the female cycle of honeycomb grouper, Epinephelus merra in Chuuk. Developmental Reproduction 7((1)): 23-28. 

Soyano, K. Matsumoto, T., Tanaka, H. & Nakamura, M. 2003. Lunar-related spawning in honeycomb grouper. Epinephelus merra. Fish Physiology and Biochemistry 28: 447-448.

Speare, P., Cappo, M., Rees, M., Brownlie, J. & Oxley, W. 2004. Deep water fish and benthic surveys in the Lord Howe Island Marine Park (Commonwealth Waters): February 2004. Townsville : Australian Institute of Marine Sciences. 30 pp. 
Stewart, B.D. & J.S. Beukers (2000). Baited technique improves censuses of cryptic fish in complex habitats. Marine Ecology Progress Series 197: 259-272.

Stewart, B.D. & G.P. Jones (2001). Associations between the abundance of piscivorous fishes and their prey on coral reefs: implications for prey-fish mortality. Marine Biology 138(2): 383-397. 

Yearsley, G.K., Last, P.R. & Ward, R.D. (eds) 1999. Australian Seafood Handbook. Hobart : CSIRO Marine Research 460 pp.

Quick Facts

CAAB Code:37311063

Biology:Able to change sex

Conservation:IUCN Least Concern

Depth:1-50 m

Habitat:Reef associated

Max Size:35 cm TL

Species Maps

CAAB distribution map