Sickelfish grouper (Dermatolepis inermis)

Also known as: donkey fish, marbled grouper, mutton hamlet, rockhind
Synonyms: Dermatolepis marmoratus, Dermatolepis zanclus, Epinephelus inermis, Serranus inermis
French: Merou Marbre
Spanish: Boricua, Cherna Jaspeada, Mero Marmal, Mero Tigre, Viuda
GenusDermatolepis (1)
SizeLength: up to 90 cm (2)

The sickelfish grouper is classified as Near Threatened (NT) on the IUCN Red List (1).

A large predatory fish of coral reefs in the western Atlantic, the sickelfish grouper (Dermatolepis inermis) is mottled greyish-brown, with white speckling and small black spots loosely arranged into rings (2). The body is deep and compressed, with large, rounded fins. The head is steep, with the heavily-lipped mouth facing upwards. The front of the dorsal fin has eleven spines, while the front of the anal fin has three. The juvenile sickelfish grouper is black or dark brown and covered with irregular white spots and blotches (3).

The sickelfish grouper is a western Atlantic species with two distinct populations. One population ranges from the mid-eastern coast of the US, eastwards to Bermuda and southwards through the Gulf of Mexico and the Caribbean to Venezuela. The other population occurs from northern to south-eastern Brazil (1).

A reef-dwelling species, the sickelfish grouper is usually found around deep crevices and ledges, down to depths of around 210 metres (1).

Little is known about this rare and secretive species but, like other groupers, it is a carnivore that ambushes its fish and crustacean prey (2) (4).

Similar to other grouper species, the sickelfish grouper is probably solitary, but forms spawning aggregations of hundreds of individuals when breeding (1). During this time, sperm and eggs are synchronously released, with fertilisation occurring in the water (3). The eggs hatch into larvae that drift passively in the ocean currents as part of the zooplankton community, before becoming juveniles and hiding within sea-grass (5). Remarkably, most groupers begin life as females, becoming male after reaching a certain age or length (4).

As a result of overfishing, the adult sickelfish grouper is now a rare species and its populations are declining (1). Due to its rarity, it is not a viable food source and is of little commercial importance to the fishing industry (3). However, it is still at risk from further overfishing, especially in spawning areas where aggregations could become easy prey for fisheries. Juvenile sickelfish groupers are also captured for the aquarium trade (1).

The sickelfish grouper occurs in Marine Protected Areas in some parts of its range. Further surveys are required to determine the location of potential spawning sites so that they can be afforded protection (1).

For more information on conservation in Bermuda:

 For more information on fish conservation in the Atlantic Ocean:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (September, 2010)
  2. McEachran, J.D. and Fechhelm, J.D. (2005) Fishes of the Gulf of Mexico. University of Texas Press, Texas, USA.
  3. Heemstra, P.C. and Randall, J.E. (1993) Groupers of the world (family Serranidae, subfamily Epinephelinae). FAO Species Catalogue, 125(16): 66-67. Available at:
  4. Goldstein, R.J. (2008) Marine Reef Aquarium Handbook. Barron’s Educational Series, Inc, New York, USA.
  5. Florida Museum of Natural History (October, 2010)