Harlequin Filefish (Oxymonacanthus longirostris)

The Harlequin Filefish, also known as the Orange-Spotted Filefish, is a stunning yet challenging species renowned for its bright blue-green body covered with orange spots. This unique fish is primarily a coral feeder in the wild and requires a specialized diet and stable environment. The Harlequin Filefish is best suited to experienced aquarists who can maintain a carefully controlled tank with regular feedings. While it can thrive in fish-only tanks, it may pick at soft corals if kept in a reef setup.

Care Information

• Maximum Size: Up to 4 inches.
• Tank Size: 30 gallons minimum; requires a well-established tank with rockwork and moderate flow.
• Diet: Omnivorous; primarily feeds on coral polyps in the wild. In captivity, it may accept a specialized diet including frozen mysis shrimp, brine shrimp, and marine algae. Consistent feedings and live rock with natural biofilm can help support its dietary needs.
• Water Temp: 72-78°F.
• Salinity: 1.020-1.025.
• Aggression: Peaceful; generally non-aggressive and best kept with other peaceful tankmates.
• Skill Level: Advanced; requires a stable, mature tank with specific dietary needs, making it suitable for experienced aquarists.
• Reef Compatibility: With caution; it may pick at soft corals, polyps, and some ornamental invertebrates. Best suited for fish-only or carefully selected reef tanks.

Special Feeding Requirements - Coral Feeder
The Harlequin Filefish is a specialized feeder, primarily consuming coral polyps in its natural habitat. In captivity, providing a varied diet with frequent, small feedings is essential, and some aquarists may need to supplement with live or enriched food options.

Compatibility
The Harlequin Filefish is peaceful and does well with other non-aggressive species. Avoid pairing it with aggressive tankmates that might stress it or outcompete it for food. It’s best housed in a species-specific tank or with carefully selected tankmates.

Coloration

• Indo-Pacific Region: The Harlequin Filefish displays a vibrant blue-green body with scattered orange spots, adding a striking splash of color to any tank. Its unique appearance and specialized behaviors make it a standout species for advanced hobbyists​.

Typical Habitat

• Distribution: Found throughout the Indo-Pacific, particularly in coral-rich reefs where it grazes on coral polyps. In aquariums, it thrives in stable, mature tanks with sufficient live rock and peaceful tankmates.