Double Saddle Butterflyfish

The Double Saddle Butterflyfish, Chaetodon ulietensis, is a deep-bodied, laterally compressed species that reaches roughly 6 inches. The white flanks are crossed by fine vertical gray lines and interrupted by two conspicuous dark saddles across the upper body, while a black bar masks the eye and a dark marking sits on the caudal peduncle. Yellow washes the rear third of the body along with the dorsal, anal, and tail fins. Aquarists occasionally confuse it with the Indian Ocean Falcula Butterflyfish, Chaetodon falcula, though the two are distinguished by the shape and placement of their dark markings. The species ranges widely through the Indo-Pacific, favoring coral-rich lagoons and appearing less frequently on seaward reefs.

Adult housing should begin at 120 gallons, and a mature, well-established system is strongly preferred over a freshly cycled one. Build the aquascape with abundant live rock arranged into sheltered retreats and grazing surfaces, and leave broad open lanes for a fish that patrols steadily through the day. Strong filtration, good oxygenation, and areas of brisk current suit a species accustomed to reef slopes and lagoon edges. Stable water chemistry matters more than any single parameter, since butterflyfishes respond poorly to swings. Care level is moderate, largely because of dietary demands and the need for a settled, food-rich environment.

In the wild, Chaetodon ulietensis takes both plant and animal material, grazing algae while picking at benthic invertebrates. Documented prey includes coral polyps, zoanthids, worms, hydroids, tunicates, and anemones, which explains both its specialized feeding apparatus and its unsuitability for reef displays. In the aquarium, the goal is to replicate that variety rather than rely on a single item. Offer mysis, enriched brine shrimp, and finely chopped clam, mussel, cockle, crab, shrimp, and squid, supplemented with Spirulina- or nori-based preparations to cover the herbivorous portion of the diet.

Feed small portions several times daily rather than one large meal, which matches the near-continuous picking behavior of wild fish. Newly acquired specimens are sometimes reluctant to begin feeding; clam or mussel presented on the half shell, live foods, or soft food pressed into crevices in dead coral often triggers the first response. Smaller juveniles reportedly adapt to captive foods more readily than large adults, so selecting a modestly sized, actively feeding specimen improves the odds of long-term success.

Mysis Shrimp Enriched Brine Shrimp Chopped Clam Chopped Mussel Chopped Squid Chopped Shrimp Nori Spirulina-Based Foods
Wild adults are found singly, in pairs, or in small groups, and pairing is common. In the aquarium the species is peaceful and typically shy on arrival, spending its first days near rockwork before venturing into open water. Adequate retreats shorten that settling period considerably, and once established the fish often becomes an assertive competitor at feeding time. Crowding is the main trigger for territorial displays, so generous swimming space is a behavioral requirement rather than a luxury. Individual temperament varies, and any specimen should be observed as it settles.

If multiple individuals or other peaceful butterflyfishes are planned, introduce them simultaneously into a spacious system to avoid established residents claiming territory. This species is not reef safe. It readily nips or consumes stony coral polyps, soft corals, zoanthids, mushroom corals, anemones, tubeworms, hydroids, and tunicates, and it may pick at crustaceans. Reports that it consumes Aiptasia are accurate but do not make it a safe reef inhabitant, since desirable sessile invertebrates face the same risk. House it in a fish-only system with live rock alongside similarly peaceful, appropriately sized companions.

FAQ

Frequently Asked Questions

About the Double Saddle Butterflyfish

  • How large an aquarium does an adult Double Saddle Butterflyfish need?
    Plan on at least 120 gallons for a single adult, with extensive live rock and long, unobstructed swimming lanes. Additional volume is valuable if other butterflyfishes will share the system.
  • Can this butterflyfish be kept in a coral reef aquarium?
    No. It feeds naturally on sessile invertebrates and will nip or consume corals, zoanthids, anemones, and tubeworms, and it may also investigate crustaceans.
  • What should be offered if a newly acquired specimen refuses food?
    Try live enriched brine shrimp, clam or mussel on the half shell, or soft food pressed into crevices in dead coral. Once the fish is feeding, transition to varied frozen meaty items and algae-based foods given in small portions several times daily.