The Masked Rabbitfish, Siganus puellus, is a large, laterally compressed grazer that reaches roughly 15 inches as an adult. The body carries yellow across the dorsal surface, grading through pale blue into white along the lower flanks, and is overlaid with fine wavy blue lines and scattered blue ventral spotting. The fins are yellow, and a bold dark diagonal band runs through the eye to form the mask that gives the species its name. Its range spans the Indo-West Pacific, where it occupies coral-rich lagoons and seaward reef slopes.

Adult housing begins at 180 gallons in a well-established marine system. Broad, uninterrupted swimming lanes matter as much as total volume for a fish of this size and activity level, so aquascape with purpose rather than filling the tank with rock. Live rock carrying established algae growth gives the fish natural grazing surfaces and helps settle new arrivals into a routine. Care level is moderate, largely because of the size requirement and the need for consistent vegetable-rich feeding.

The stout dorsal and anal spines are venomous and can deliver a painful sting. Handle the fish with deliberate caution during capture, transfer, and any maintenance that brings hands near it, and use a container rather than a net whenever practical to avoid tangling the spines.

This species is an omnivore with a strong herbivorous bias in early life. Juveniles in the wild graze filamentous algae, while adults broaden their intake to include algae, tunicates, and sponges. One field study found that sponge material dominated the stomach contents of sampled adults, with bryozoans and hydrozoans also present, so the adult diet is considerably more varied than a simple algae grazer.

In the aquarium, build the diet around vegetable matter. Dried seaweed offered on a clip, Spirulina-based preparations, live or fresh macroalgae, and frozen herbivore blends all belong in the rotation. Feed several times daily to match the near-constant grazing pattern of the species. Newly introduced individuals sometimes refuse prepared foods at first; enriched adult brine shrimp and live macroalgae are useful tools for triggering an initial feeding response before transitioning to the standard menu.

Dried Seaweed Spirulina Preparations Macroalgae Frozen Herbivore Blends Enriched Adult Brine Shrimp
Masked Rabbitfish are active swimmers that patrol open water and rockwork throughout the day. Small juveniles gather in large schools over shallow reef flats and lagoons, but adults are typically encountered in pairs. Keep one individual per aquarium unless a compatible mated pair is available, since multiple unpaired adults are a poor prospect in captive volumes.

Temperament is peaceful, and this species mixes reasonably with peaceful to moderately aggressive tankmates in a system of appropriate size. It may, however, chase other herbivores competing for the same grazing territory, so plan the herbivore roster carefully. The venomous spines also warrant respect from tankmates, and aggressive fish that harass it risk injury. Reef compatibility is with caution: the species may consume or damage some soft corals, Xenia in particular, and its safety with other invertebrates is not assured. Generous vegetable feeding and ample grazing surfaces reduce, but do not eliminate, the risk to sessile livestock.

FAQ

Frequently Asked Questions

About the Masked Rabbitfish

  • How large an aquarium does an adult Masked Rabbitfish require?
    Plan on a minimum of 180 gallons for an adult. The system should offer substantial open swimming room along with live rock for grazing.
  • Is the Masked Rabbitfish fully reef-safe?
    No. It is reef-safe with caution, as it may damage some soft corals including Xenia, and its compatibility with other invertebrates is not assured.
  • Should this species be kept singly or in a group?
    Keep one per aquarium unless you have a compatible mated pair. Juveniles school in nature, but adults normally occur in pairs, and captive individuals may chase other herbivores.