Three Band Pennant Butterflyfish - Heniochus chrysostomus

Introduction to Three-Band Pennant Butterflyfish (Heniochus chrysostomus)

The Three-Band Pennant Butterflyfish is a graceful and eye-catching species known for its tall dorsal “banner” fin and bold black-and-white banding. Often confused with Moorish Idols due to its similar shape, this species is a much more manageable alternative for aquariums. Native to Indo-Pacific reefs, they are active swimmers that do best in groups or pairs and add constant movement to the tank. Their striking appearance and schooling behavior make them a popular choice for larger fish-only systems.

Care Requirements

Care Level: Moderate
Minimum Tank Size: 125+ gallons
Aquarium Setup: Requires ample open swimming space, stable rockwork, and strong filtration

Three-Band Pennant Butterflyfish are active and benefit from tanks that provide both open water for swimming and rockwork for shelter.

Diet & Nutrition

These butterflyfish are omnivores that adapt relatively well to a variety of prepared foods.

Diet: Omnivorous – Requires a mix of meaty and plant-based foods

Recommended Foods:

• Mysis shrimp, brine shrimp, and chopped seafood
• High-quality frozen blends
• Spirulina-based foods and algae sheets
• Pellets and flakes once acclimated

Offering a varied diet helps maintain their health and coloration.

Lifespan & Growth Rate

Lifespan: 5–10+ years
Growth Rate: Moderate – Can reach up to 6–7 inches

They grow steadily and remain active swimmers throughout their lifespan.

Temperament & Compatibility

Temperament: Peaceful to Semi-Aggressive
Reef Safe? No – Will nip at corals and invertebrates

Three-Band Pennant Butterflyfish do well with other peaceful to moderately aggressive fish but are best kept in fish-only systems due to their tendency to pick at corals.

Common Challenges & Considerations

• Not Reef Safe: Known to nip at corals and sessile invertebrates
• Active Swimmer: Requires a large tank with plenty of space
• Best in Groups: Can be kept singly, but often do better in pairs or small groups
• Misidentification: Often confused with Moorish Idols, which have very different care requirements

Water Conditions

Temperature: 75–77°F
dKH (Alkalinity): 8–12
pH: 8.1–8.3
Specific Gravity: 1.024–1.026