Humpback grouper  (Cromileptes altivelis)

This extraordinary-looking fish is often called the panther, or ‘polka-dot' grouper for its striking colour pattern of bold black spots against a white to creamy-grey body (3). Juveniles display fewer, larger black spots, which become smaller and more plentiful as the fish matures (4). When disturbed, individuals may develop a ‘fright colouration', in which large brown blotches colour the skin (3). This unusual fish is also unique amongst the groupers in having an elongate, slender head that rises sharply at the nape of the neck, giving the species the distinctive ‘humpback' appearance for which it is named (5). The long dorsal fin begins at the top of this ‘hump' and extends almost the entire length of the body (6).

Found in the Western Pacific, from southern Japan to Palau, Guam, New Caledonia and southern Queensland, Australia; and the Eastern Indian Ocean, from the Nicobars to Broome, Western Australia (7). There is also a report from the Western Indian Ocean (Kenya) that has not been confirmed (1). Records from Hawaii are thought to be based on released aquarium fish (7).

The humpback grouper generally inhabits lagoons and seaward reefs, where it is typically found in dead or silty areas, to depths of up to 40 meters (1) (7). It also occurs around coral reefs and in tide pools, while juveniles tend to confine themselves to shallow, protected reefs (1).

The humpback grouper is known to be territorial and somewhat aggressive, particularly towards smaller fish. This solitary predator hides in the rocks before ambushing its prey (6), which typically comprises fish and crustaceans (5). It is thought that the species' ‘polka-dot' pattern of colouration may disrupt the contour of its body and thereby help camouflage it from prey and would-be predators (6).

Females lay eggs that are then fertilised by the male externally, and neither the eggs nor hatched young are guarded or protected in any way by the parents. Only females hatch, with males being produced as necessary by the dominant females within a group changing sex from female to male. If a male dies, the next dominant female will undergo a sex change to replace him (6).

The humpback grouper is threatened in Southeast Asia, where it is heavily exploited and its habitat is being degraded. This species is one of the most highly valued species in the live food fish trade centre in Hong Kong, where many tonnes are sold, coming principally from Indonesia, the Philippines and the Chinese Islands (1). Large adults are most likely to be harvested for the food fish trade, while smaller individuals that are used in the aquarium trade tend to come from hatchery produced mariculture (8).

The humpback grouper is reportedly farmed commercially in Bali, Indonesia, although the annual production is not known. Furthermore, cultured animals are presently sold in the aquarium market rather than for food, for which individuals must be harvested from the wild. There is a minimum capture size of 40 centimetres for this species in Queensland and recreational fishers are restricted to one fish each (1).

Authenticated (19/03/07) by Yvonne Sadovy, Society for the Conservation of Reef Fish Aggregations (SCRFA).
http://www.scrfa.org/