Three Band Pennant Butterflyfish - Heniochus chrysostomus

Small (<2")

$69.99

Three Band Pennant Butterflyfish - Heniochus chrysostomus

Butterfly EXPERT ONLY Reef Safe Caution

$69.99

SKU: BUTTERxPennantS

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Diet

mysis shrimp brine shrimp finely chopped meaty foods

Min Tank Size 125 gallons

Temperament Semi-aggressive

Reef Safe No

Care & Diet Feeding, nutrition, and best practices.

Diet Type: Omnivore

Diet and Feeding: Three Band Pennant Butterflyfish are primarily omnivorous with a strong preference for algae, filamentous seaweed, and small invertebrates in the wild, so it is beneficial to build the captive diet around marine algae-based foods such as nori, dried seaweed, spirulina flakes, and quality herbivore/omnivore pellets. To ensure balanced nutrition, supplement regularly with small portions of frozen mysis, enriched brine shrimp, finely chopped clam, and other meaty marine fare as occasional treats. Offer seaweed on a clip and provide small, varied feedings in more than one location to encourage natural foraging and reduce aggression. Feed small amounts two to three times daily, and avoid overfeeding to maintain water quality and support long-term health.

mysis shrimp brine shrimp finely chopped meaty foods

Behavior Temperament, activity level, and interactions.

Temperament: Semi-aggressive

The Three Band Pennant Butterflyfish is an active, midwater swimmer that needs plenty of open space along with rockwork or caves for retreat, so it does best in a spacious aquarium with defined swimming lanes. Temperament is generally peaceful toward dissimilar tank mates but can be assertive with conspecifics, especially in smaller systems where territorial spacing is limited. A minimum tank size of 100 gallons is recommended, and the use of visual barriers created by live rock helps reduce stress and aggression by breaking up lines of sight. It typically coexists well with other non-aggressive, similarly sized reef-safe species, but it is not considered reliably reef-safe with corals or other sessile invertebrates. Diet-wise, it is an omnivorous microcarnivore that forages for small benthic invertebrates, zooplankton, and sponge-based foods, and in captivity should be offered a varied diet of enriched frozen meaty foods and quality prepared marine formulations.

Tank & Aquascape Tank requirements and aquascaping tips.

Min Tank Size: 125 gallons
Max Size: 8 inches
Care Level: Hard
Origin: Indo-Pacific

Compatibility Tank mates, aggression, and introduction order.

Temperament: Semi-aggressive
Reef Safe: No

Reef & Health Reef safety, common issues, and prevention.

Reef Safe: No
Care Level: Hard

FAQs Answers to the most common questions.

How large does a Three Band Pennant Butterflyfish get, and what tank size is actually appropriate for long-term care?

Adults typically reach about 8–9 inches (20–23 cm). Because they are active, open-water cruisers that also need room to graze and inspect rockwork, a long tank of at least 125 gallons is a realistic minimum for a single specimen. Bigger is better, especially if you want to keep it in a reef-style aquascape with ample swimming space and stable water quality.

Is a Three Band Pennant Butterflyfish reef safe, and what corals or invertebrates are most at risk?

It is not considered reef safe. Even well-fed individuals commonly nip at soft corals, LPS, zoanthids, and feather dusters, and they may also pick at anemones, tube worms, clam mantles, and small ornamental crustaceans. Some individuals ignore certain corals for a while, but this species should be treated as a coral predator with unpredictable reef compatibility.

What should I feed a Three Band Pennant Butterflyfish, and how do I get one to eat in captivity?

They do best on a varied diet with a strong meaty component: mysis shrimp, finely chopped seafood, enriched frozen marine preparations, and high-quality marine pellets. Many also benefit from frequent small feedings and occasional sponge-based foods, since butterflyfishes often do well when sponge material is included in the diet. Newly imported fish can be difficult, so live blackworms, clam on the half shell, or small pieces of fresh seafood are often used to trigger feeding. Once eating, consistency and variety are key.

Can Three Band Pennant Butterflyfish be kept with other butterflyfish or aggressive tankmates?

They are usually peaceful to semi-aggressive and can be intimidated by assertive tankmates. They may also show territorial behavior toward similar-shaped butterflyfish, especially in smaller tanks. Best results come from housing them with calm to moderately active fish such as tangs, wrasses, angelfish of appropriate size, and other non-bullying species. Avoid placing them with aggressive triggers, large puffers, or highly territorial butterflyfish unless the system is large and carefully planned.

What water conditions and husbandry details are most important for keeping a Three Band Pennant Butterflyfish healthy long term?

Stability matters more than chasing exact numbers, but they generally thrive in tropical reef conditions: temperature around 75–80°F (24–27°C), salinity 1.023–1.026, pH 8.1–8.4, and strong oxygenation with excellent filtration. They are sensitive to poor water quality and shipping stress, so pristine conditions, low nitrate, and a properly quarantined, disease-screened specimen are important. They also appreciate plenty of live rock for shelter and grazing, but the layout should still leave open swimming lanes.

Goes well with:

**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