Boenacki (Blueline) Grouper

The Boenacki (Blueline) Grouper (Cephalopholis boenak) is a distinctive marine predator. This compact hind has brown to reddish coloration, darker bars, and fine blue edging or markings that give it its Blueline trade name.

Indo-West Pacific. It is associated with reef structure and nearby sheltered bottom habitat, using cover while resting or watching for prey. A mature aquarium with secure shelter and a reliable feeding routine allows its natural behavior to be observed without placing smaller livestock at unnecessary risk.

Plan housing around the adult fish. It is smaller than many groupers but still territorial and predatory. Keep one unless an exceptionally spacious, carefully planned system provides separation.

Quick Care Guide

Care Level: Moderate
Minimum Tank Size: 125 Gallons
Adult Size: Up to 11.8 inches (30 cm)
Temperament: Aggressive
Diet: Carnivore
Reef Safe: No
Region: Indo-West Pacific
Scientific Name: Cephalopholis boenak

Tank Requirements

Provide an established aquarium of at least 125 gallons for adult housing, with larger systems preferred. The footprint must allow comfortable turning and full access to shelter. It is smaller than many groupers but still territorial and predatory. Keep one unless an exceptionally spacious, carefully planned system provides separation.

Arrange heavy rockwork on a stable base with wide caves and overhangs that can contain the adult body. Leave open swimming lanes and keep equipment protected from sudden feeding movements. Use a secure cover, dependable biological filtration, effective protein skimming, and good surface gas exchange. A roomy aquarium with inaccessible waste pockets still needs an effective maintenance plan.

Make shelter entrances wide enough for growth and keep rock structures stable. Avoid repeated rearrangement during settling. A fish spending most of its time under cover still needs room to turn and emerge without scraping against decorations.

Diet and Feeding

Offer a varied carnivorous diet of marine fish, shrimp, squid, clam, mussel, and balanced marine carnivore preparations. Match portions to the mouth and body condition. Feed growing juveniles smaller meals more frequently; established larger adults often suit several measured meals per week. Avoid a routine diet of freshwater feeder fish or dependence on one food such as krill.

Use a feeding routine that lets you observe intake and condition. Do not leave uneaten seafood inside caves or encourage feeding to extreme fullness. Remove remains promptly and investigate sustained refusal, rapid breathing, or visible weight loss rather than simply offering larger quantities. Keep hands away from the mouth and use appropriate feeding tools.

Temperament and Tankmates

An ambush predator can remain still for long periods and then strike very quickly. Keep a single grouper as the default and choose robust, non-bullying tankmates that cannot be swallowed, judging body depth as well as length. Small fish and ornamental crustaceans are potential prey. Additional groupers require much more space and a practical separation plan.

Watch for blocked access to caves, injuries, and persistent hiding after a new introduction. Feeding the predator well does not make prey-sized tankmates safe, and apparent juvenile compatibility may change as fish mature.

Reef Compatibility

Not recommended for conventional mixed reefs. Healthy coral tissue is not the usual target, but small fish, shrimp, crabs, and other suitable mobile animals may be eaten. Larger individuals can disturb unsecured coral and rockwork. A fish-focused display with carefully selected tankmates is the practical setting.

Water Parameters

Temperature: 75–79°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Maintain stable, well-oxygenated marine water with undetectable ammonia and nitrite. Match acclimation to the supplier's holding conditions, avoid rapid changes, and maintain filtration for the actual feeding load.

Common Considerations

• Adult commitment: Up to 11.8 inches (30 cm). Plan the aquarium and every tankmate accordingly.
• Food and filtration: Varied marine nutrition and prompt waste removal support long-term condition.
• Shelter: Provide secure retreats with comfortable adult clearance.
• Predation: Mouth-sized fish and mobile invertebrates are at risk.
• Species considerations: It is smaller than many groupers but still territorial and predatory. Keep one unless an exceptionally spacious, carefully planned system provides separation.