The Panther Grouper (Chromileptes altivelis) is a distinctive marine fish sought after in both the commercial food fish market and the ornamental aquarium trade. It is also commonly referred to as the Humpback Grouper, Barramundi Cod, or Polka-Dot Grouper, reflecting its unique appearance. While it does not reach the colossal proportions of some grouper relatives, the Panther Grouper attains a substantial size, making it a formidable presence in its native Indo-Pacific reef habitat.
Maximum Reported Size and Weight
The maximum recorded length for a wild Panther Grouper is consistently reported to be around 70 to 71 centimeters (approximately 2.3 feet) in total length. These record-breaking individuals are typically found in deep, undisturbed waters, where they have lived for many years.
While weight records are less common than length measurements, a specimen approaching this maximum length, measuring 68 centimeters, was noted to weigh roughly 15 pounds (about 6.8 kilograms). This weight demonstrates the significant mass these fish can accumulate when they reach their full potential size. Achieving this size reflects an extensive lifespan, with the species having the capacity to live for at least 19 years in the wild, and some estimates suggesting up to 40 or 50 years under ideal conditions.
Typical Adult Dimensions and Growth Rate
The average size of a mature Panther Grouper encountered by fishermen or divers is considerably less than the recorded maximum. Most adult fish in the wild or commercial catch typically measure between 50 and 65 centimeters (about 20 to 26 inches). Aquarium specimens often reach 24 to 27 inches (61 to 68.6 centimeters) when housed in exceptionally large systems.
The growth trajectory of this species is relatively slow compared to many other commercially farmed fish. After reaching sexual maturity, which can occur around 1.5 to 2 years of age, their growth rate slows down significantly. In the adult phase, a well-fed individual might increase its length by only 2 to 3 inches annually. This sustained, slow growth over many years allows the species to eventually attain its impressive adult dimensions.
Environmental Influences on Final Size
The ultimate size a Panther Grouper reaches is heavily influenced by a combination of environmental factors. The availability and quality of food plays a direct role in the rate of growth and final body mass. Abundant food resources and a consistent diet allow for faster development and a larger mature size compared to those in resource-scarce areas.
Habitat depth is another significant variable, with individuals residing in deeper waters sometimes exhibiting a faster growth rate than those living in shallower reefs. Population density can also affect growth, as competition for food and space limits the resources available to each fish. Individuals raised in aquaculture or the aquarium trade often experience size constraints due to restricted space and controlled diets, resulting in a slightly smaller final size than their wild counterparts.
Distinctive Appearance and Identification
The most noticeable feature is the distinct pattern of dense, dark black spots, or polka-dots, that cover its entire body, head, and fins, contrasting against a pale background color that can range from white to cream or greenish-brown. The spots tend to be larger and more pronounced on juveniles, becoming smaller and more numerous as the fish matures.
The species’ common name, Humpback Grouper, is derived from its unusual body shape, which is vertically compressed and has a unique head profile. The top of the head is depressed and concave, leading to a sharply elevated and high dorsal area that gives it a characteristic hump-like silhouette. This elongated, tall profile, combined with a relatively large mouth and rounded fins, gives the Panther Grouper an unmistakable and striking appearance in the marine environment.