Bristletail Filefish

Geographic Origin and Biotope: Common in the Western tropical Pacific, from Indonesia and the Philippines to northern Australia and the Solomon Islands. Inhabits shallow seagrass beds, coastal reefs, and silty or rubble-rich zones at depths of 1 to 15 meters.

Taxonomy and Morphology: Member of the Monacanthidae family. Features a compressed body covered in tiny prickles giving it a bristletail appearance. Has a lockable first dorsal spine. Grows to 12 cm (4.7 inches).

Social Behavior: Peaceful and slow-moving. Relies on color-changing camouflage to blend in with seagrasses or rocks. Can be shy initially.

Coloration and Sexual Dimorphism: Highly variable mimetical color pattern, blending olive-green, brown, and grey with dark mottling. Adult males display a patch of bristle-like spines on the caudal peduncle, which is absent in females.

Aquarium Setup: Needs at least 120 liters of volume with plenty of live rock, macroalgae, and sand. Water flow should not be overly strong due to their weak swimming ability.

Diet and Feeding: Opportunistic omnivore. Eats pest Aiptasia and Majano anemones. Provide frozen mysis, brine shrimp, chopped krill, spirulina pellets, and dried marine algae. Feed twice daily.

Water Quality: Hardy and tolerant. Standard reef parameters: temperature 24-26°C (75-79°F), pH 8.1-8.4, specific gravity 1.020-1.025, GH 15-25, and KH 8-12.

Compatibility and Tankmates: Reef-safe with caution. While it controls pests, it may nip at soft corals, LPS (like zoanthids or Xenia), and clam mantles if underfed. Avoid aggressive tankmates.

Aquarium Reproduction: Feasible. Eggs are laid on substrate or algae and guarded by the pair until hatching. Rearing larvae is complex.

Risks and Diseases: Very resilient. Main risk is starvation if kept with fast, hyperactive fish that outcompete it during feeding.