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