Polleni Grouper

Also known as the Harlequin Grouper or Harlequin Bass

The Polleni Grouper is a striking and moderately-sized predatory species that displays exceptional spotted coloration and a bold personality. Native to the Western Indian Ocean, particularly around Madagascar, the Comoros, and East Africa, this distinctive hunter features a creamy white to pale body covered with large dark spots and elegant flowing fins. While their predatory nature requires careful tankmate selection, their manageable size and stunning appearance make them an attractive option for intermediate to advanced aquarists with appropriately sized systems.

Key Features

• Scientific Name: Cephalopholis polleni
• Common Names: Polleni Grouper, Harlequin Grouper, Harlequin Bass, Harlequin Rockcod
• Adult Size: 12–16 inches (30–40 cm); commonly 12–14 inches in aquariums
• Lifespan: 10–15 years with proper care
• Temperament: Aggressive and predatory; will consume fish half their size or smaller
• Reef Compatibility: Not reef-safe – predatory toward small fish and ornamental invertebrates
• Minimum Tank Size: 180 gallons minimum (240+ gallons recommended)
• Experience Level: Intermediate to Advanced – requires predator experience

Habitat & Tank Requirements

Natural Habitat: Found on coral reefs, rocky outcrops, and caves at depths of 15–130 feet. Prefers areas with abundant hiding spots where they can ambush prey.

Tank Environment:

• Multiple caves and overhangs for shelter
• Secure rockwork with hiding spots
• Moderate swimming space
• Strong biological filtration for bioload
• Subdued to moderate lighting
• Heavy, secure lid essential

Water Parameters:

• Temperature: 74–80°F (23–27°C)
• Salinity: 1.023–1.025 specific gravity
• pH: 8.1–8.4
• Ammonia/Nitrite: 0 ppm
• Nitrate: <30 ppm
• Alkalinity: 8–12 dKH

Diet & Feeding

Recommended Foods:

• Fresh/frozen shrimp, fish, squid, krill (primary diet)
• Live feeder fish (quarantined, occasional)
• High-quality marine carnivore pellets (supplementary)
• Varied meaty foods for complete nutrition

Feeding Schedule:

• Feed 3–4 times weekly for adults
• Juveniles require more frequent feeding (4–5 times weekly)
• Fast one day weekly
• Use feeding tongs to prevent aggression

Behavior & Compatibility

Tank Mates:

• Compatible with: Large tangs (8+ inches), large angelfish, large wrasses, triggerfish, pufferfish (similar size)
• Caution with: Semi-aggressive species that compete for food
• Avoid: All fish under 6 inches, slow-swimming species, long-finned fish, ornamental shrimp, crabs

Social Behavior:

• Best kept as single specimen
• Territorial toward conspecifics
• Ambush predator that waits in caves
• May become tame and recognize owner
• Generally remains hidden during acclimation

Reef Compatibility: Not reef-safe; will consume small fish and mobile invertebrates.

Color & Development

Coloration: Creamy white to pale yellow base covered with large, irregularly-shaped dark brown to black spots creating a harlequin pattern; distinctive blue edging on fins; spots may have blue or white halos; juveniles show more vibrant contrast that intensifies with age.

Color Intensity:

• High-protein diet maintains vibrant contrast
• Stress may cause temporary darkening
• Excellent water quality preserves pattern clarity
• Color darkens when hunting or territorial

Why Choose a Quarantined Polleni Grouper?

Our quarantine protocol includes 4–6 weeks minimum observation, preventative parasite treatment, dietary conditioning to frozen foods, and health assessment. These beautiful predators combine manageable size with spectacular spotted coloration, making them an exceptional centerpiece for experienced aquarists seeking a personable predator with striking harlequin patterning.