The humpback grouper (Cromileptes altivelis), also known as the panther grouper, (in Australia) barramundi cod, (in the Philippines, in Tagalog) lapu-lapung senorita, (in the Philippines, in Bisayan) miro-miro, (in Japan) sarasa-hata, (in India) kalava, and many other local names, is a species of marine ray-finned fish. Specifically, it is a grouper from the subfamily Epinephelinae, which is in the family Serranidae, which also includes the anthias and sea basses. It occurs in the Western Pacific Ocean.

BIOLOGY AND ECOLOGY

DESCRIPTION

• The humpback grouper is a medium-sized fish which grows up to 70 cm (28 in).

• Its particular body shape makes this grouper difficult to confuse with other fishes. Its body is compressed laterally, is relatively high, and has a unique head profile compared to other groupers.

• The head is depressed anteriorly and elevated posteriorly, with a sharp rise at the nape. This stocky and strange visual effect gives it the unique humpbacked appearance.

COLORATION

• Relating to its coloration, the young are white with round black spots.

• The adults have a body colouration with variances of grey and beige, with darker blotches variable in size on the body.

• Small black spots cover the whole body.

• In comparison, juveniles have fewer of these black spots than adults, but the spots can be larger, or as large, as their eyes.

• Furthermore, their coloration has been observed to change with a drop in pH.

 FINS

• In terms of its fins, the grouper has rounded pectoral and caudal fins, aiding in stability.

• Their pectoral fins range between 17 and 18 rays, with the middle rays being the longest.

• They also have a long dorsal fin that originates from their opercle, and runs all the way to its caudal fin.

• The dorsal fin consists of around 10 spines and 17–19 rays, which greatly aids in stability against turning.

• The anal fin, which is about half in length of the dorsal fin, consists of around 3 spines, and 9–10 rays.

• Their brush-like villiform teeth are adequate for eating smaller fish, and have smooth body scales.

DISTRIBUTION AND HABITAT

• It is widely distributed throughout the tropical waters of the central Indo-West Pacific region.

• The humpback grouper lives in clear waters from lagoons and seaward reefs with a preference for dead or silty areas.

• They are found in a range of depth from 2 to 40 m (6.6 to 131.2 ft), but usually found at depths less than 10 m (32.8 ft).

• The humpback fish has a preferendum temperature of 24.5 C, similar to other cool, temperate, freshwater fishes.

DIET

• The diet of this grouper is based on small fishes and crustaceans, such as krill, shrimp, squids, and clams.

• In human care, they are commonly fed fresh and/or dried fish.

• Like the other members of its family, the humpback grouper is demersal, solitary (except during mating periods), defends a territory, and is an ambush predator. Its feeding activity is maximal at sunrise and/or at sunset.

• Because of their carnivorous diet, C. altivepis has been commonly blamed for Ciguatera poisoning throughout their native and non-nonnative distribution.

DISEASE

• With live fish markets potentially acting as a transmitter of disease, this species has been commonly blamed for ciguatera fish poisoning cases.

• Ciguatera fish poisoning comes from consuming a fish with ciguatoxins, and the humpback grouper, amongst many other predatory fish, can easily accumulate ciguatoxins. Because of this, ciguatera 'hotspots' surrounding these markets have been a concern for human health.

• The humpback grouper is also known to be able to carry many pathogens, including Hirudinea, Pateruella, grouper iridoviruses, and more. Iridovirus is a leading cause of mortality in groupers kept in captivity, which causes lethargic swimming, darker body coloration, anemia, and more.

LIFE CYCLE AND BEHAVIOUR

• This species is a protogynous hermaphrodite; in other words, all individuals are born female, with the ability to transform to males as they grow older.

• Female humpback groupers start transitioning to males as early as 3 years. By the age of 9, most humpback groupers are male.

• Typically, only the most dominant, mature females undergo this transformation in the absence of a dominant male.

• Although primarily solitary, they are also known to swim in pairs, or sometimes in groups of 3–6. However, the direct purpose of these groups is unknown.

• Compared to other closely related groupers, the humpback grouper has a notably slow growth rate, with female humpback groupers maturing around 1.5 years.

• Interestingly enough, cryopreservation has been tested with these humpback grouper embryos, with the survival rate of 7.55% and maximum time of viability being 5 days.

• The humpback grouper's peak spawning time is between October and January, with a single spawn event lasting from 4 to 8 days.