Orange Spotted Filefish

Also known as the Harlequin Filefish or Fantail Filefish

The Orange Spotted Filefish is a stunning and unique marine fish featuring a pale body adorned with brilliant orange spots and intricate patterns. Native to the Indo-Pacific region, this peaceful species displays fascinating behavior including the ability to change coloration and lock its dorsal spine as a defense mechanism. While beautiful and personable, Orange Spotted Filefish have specialized dietary requirements and may nip at coral polyps, making them better suited for fish-only systems or aquariums with hardy corals. Their captivating appearance and interesting behaviors make them rewarding fish for aquarists prepared to meet their specific care needs.

Key Features

Scientific Name: Oxymonacanthus longirostris
Common Names: Orange Spotted Filefish, Harlequin Filefish, Longnose Filefish
Adult Size: 3–4 inches (8–10 cm)
Lifespan: 3–5 years with proper care (challenging to maintain long-term)
Temperament: Peaceful and shy
Reef Compatibility: Not reef-safe – may nip SPS coral polyps, especially Acropora
Minimum Tank Size: 30 gallons (40+ gallons recommended)
Experience Level: Intermediate to Advanced – specialized diet requirements

Habitat & Tank Requirements

Tank Environment:

• Peaceful environment with hiding spots
• Live rock structures
• Moderate water flow
• Standard reef lighting acceptable
• Acropora or other SPS corals often required for natural feeding behavior

Water Parameters:

• Temperature: 72–78°F (22–26°C)
• Salinity: 1.023–1.025 specific gravity
• pH: 8.1–8.4
• Ammonia/Nitrite: 0 ppm
• Nitrate: <20 ppm

Diet & Feeding

Natural Diet:

• SPS coral polyps (Acropora primary)
• Some specimens will nip other SPS and LPS polyps

Aquarium Foods (Training Required):

• Frozen mysis shrimp (small pieces)
• Frozen brine shrimp
• Finely chopped seafood
• High-quality pellets (rarely accepted)
• Nori sheets, spirulina (occasional)

Feeding Challenge:

• Many refuse prepared foods entirely
• May require “sacrificial” Acropora frags initially
• Gradual transition to frozen foods sometimes successful
• High mortality from starvation if won’t accept prepared foods
• Feed 2–3 times daily in small portions

Behavior & Compatibility

Temperament:

• Extremely peaceful and shy
• Non-aggressive toward all tankmates
• Often form monogamous pairs
• May hide frequently, especially when stressed
• Fascinating hovering behavior

Tank Mates:

• Compatible with: Peaceful fish only (clownfish, gobies, dartfish, cardinalfish, peaceful wrasses)
• Avoid: Aggressive fish, fast competitive feeders, large predatory fish

Reef Compatibility:

• Not reef-safe: Will nip SPS coral polyps (especially Acropora)
• May nip LPS and soft coral polyps
• Safe with most invertebrates (shrimp, crabs, snails)
• Best for fish-only or FOWLR systems
• Only suitable for reef tanks if coral polyp nipping acceptable

Health & Acclimation

Initial Acclimation:

• Extended drip acclimation over 60–90 minutes
• Dim lights during introduction
• Very shy initially; may hide for days

Health Considerations:

• Sensitive to stress and poor water quality
• Susceptible to marine ich and velvet
• Starvation common if won’t accept prepared foods
• Quarantine challenging due to feeding requirements
• Monitor body condition closely

Signs of Health:

• Rounded body (not pinched or thin)
• Active during feeding
• Bright orange spots with clear patterns
• Alert, responsive behavior

Color & Special Features

Coloration:

• Body: Pale blue-gray to white base
• Pattern: Brilliant orange spots covering entire body
• Additional Markings: Blue stripes and intricate patterns
• Color Change: Can lighten or darken based on mood and surroundings
• Absolutely stunning appearance

Unique Behaviors:

• Can lock dorsal spine erect as defense
• Often swim in pairs (monogamous)
• Hover vertically or at angles
• Change coloration based on stress or mood

Why Choose (Or Avoid) Orange Spotted Filefish?

Consider This Species If:

• You have experience with difficult feeders
• Willing to provide sacrificial Acropora or SPS frags
• Fish-only or FOWLR system
• Can acquire already-feeding specimen
• Want to keep a bonded pair

Orange Spotted Filefish are breathtakingly beautiful with captivating behaviors, but their specialized dietary requirements and coral polyp nipping make them suitable only for dedicated aquarists with appropriate systems and realistic expectations about their challenging care needs.