The armatus (Neocirrhites armatus) is a popular reef aquarium fish reaching 3.5 in (9 cm) in the home aquarium. Originating from the Central Pacific region, it is rated as easy difficulty and is generally considered reef safe with caution. Its semi-aggressive temperament makes it suitable for community reef setups when proper care guidelines are followed.
Quick facts
| Scientific name | Neocirrhites armatus |
| Max size | 3.5 in (9 cm) |
| Min tank size | 30 gal (115 L) |
| Temperament | Semi-aggressive |
| Diet | Carnivore |
| Reef safe | Caution |
| Care level | Easy |
| Origin | Central Pacific |
Overview
The following sections detail exactly how to keep this species thriving in a saltwater reef environment.
Tank requirements
Provide a minimum tank size of 30 gal (115 L) with ample live rock for grazing, hiding, and territory. Maintain standard reef parameters: temperature 75–80 °F, pH 8.0–8.4, salinity 1.024–1.026, alkalinity 8–11 dKH. Add this species later in the stocking order to minimize territorial aggression toward existing tankmates. Moderate flow and lighting that suits your coral mix work well.
Water parameters
Maintain standard reef aquarium parameters for long-term health:
- Temperature: 75–80 °F (24–27 °C)
- pH: 8.0–8.4
- Salinity: 1.024–1.026 sg
- Alkalinity: 8–11 dKH
- Ammonia / Nitrite: 0 ppm
- Nitrate: < 20 ppm (lower is better for a reef)
Stability is more important than hitting a specific number. Avoid sudden swings in any parameter.
Diet and feeding
Feed a carnivore diet consisting of frozen Mysis shrimp, enriched brine shrimp, and marine pellets. Feed 1–2 times daily in small amounts consumed within two minutes. Vary the diet to ensure complete nutrition and vibrant coloration.
Behavior and compatibility
This species has a semi-aggressive temperament and may be territorial toward similar-looking species or conspecifics. Best kept singly or in a mated pair in tanks under 75 gallons. Monitor for coral nipping behavior—while uncommon, some individuals may pick at LPS polyps or clam mantles.
Breeding
Breeding Neocirrhites armatus in captivity is possible for dedicated hobbyists. Sexing can be difficult without observing spawning behavior.
Tips for success
- Quarantine for at least 2–4 weeks before adding to your display tank.
- Provide 30 gal (115 L) minimum—larger is always better for long-term health.
- Vary between frozen, pellet, and live foods for optimal nutrition.
- Maintain stable water parameters—sudden changes cause stress and disease susceptibility.
- Observe the fish eating at the store before purchasing to ensure it is feeding well.
Frequently asked questions
What tank size does a Neocirrhites armatus need?
The minimum recommended tank size is 30 gal (115 L). This provides adequate swimming space, territory, and stable water volume. Larger tanks are always better, especially for active swimmers.
Is this fish reef safe?
This species is generally reef safe but some individuals may nip at coral polyps or clam mantles. Monitor after introduction and have a backup plan.
What does this fish eat?
This is a carnivore species. Feed meaty foods: frozen Mysis shrimp, enriched brine shrimp, and high-quality marine pellets.
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