Common name: Oneknife Unicornfish
General Information
The Oneknife Unicornfish, scientifically known as Naso thynnoides, is a fascinating species popular among aquarium enthusiasts for its unique appearance and relatively peaceful nature. Recognizable by its elongated body, prominent dorsal spines, and a distinctive single blade located near the caudal peduncle, this species is a captivating addition to any large marine aquarium.
In the wild, the Oneknife Unicornfish inhabits coral reefs and rocky outcrops across the Indo-Pacific region, from the Red Sea and East Africa to the Hawaiian Islands and French Polynesia. Its natural habitat consists of clear, warm waters, where it often forms schools with other herbivorous fish.
Details
- Estimated price
- Moderate
- Recommended minimum tank volume
- 500 liter (130 gallons)
- Salinity
- S.G. 1.023 to 1.026
- Temperature
- 24 to 28 °C (75 to 82 °F)
- Acidity
- pH 8 to 8.4
- Average size
- 50 cm (1′8″)
- Care level
- Moderate to difficult Requires a large tank due to its size and active nature
- Diet
- Herbivore Feed on marine algae, seaweed, and high-quality herbivore pellets
- Social
- School Best kept in groups to mimic natural schooling behavior
- Reefsafe
- Yes
- Aggression
- Peaceful Generally peaceful but may be territorial with conspecifics
- Captive bred
- No
- Conservation statusSource: IUCN Red List
Taxonomy
- KingdomAnimalsAnimalia
- PhylumChordatesChordata
- ClassRay-finned FishesActinopterygii
- OrderPerch-like FishesPerciformes
- FamilySurgeonfishAcanthuridae
- GenusUnicornfishNaso
- SpeciesOneknife UnicornfishNaso thynnoides (Cuvier, 1829)
- SynonymsAxinurus thynnoides Cuvier, 1829
- Source: GBIF | Global Biodiversity Information Facility
Care
Caring for the Oneknife Unicornfish requires a spacious tank, as these fish are active swimmers and can grow quite large. A minimum tank size of 500 liters is recommended to accommodate their need for space. They thrive in well-oxygenated water with stable conditions, and a tank setup that mimics their natural reef environment will help them feel at home.
Providing plenty of live rock and open swimming areas is essential. These fish are known to graze on algae, so a tank with natural algae growth can be beneficial. Additionally, maintaining high water quality through efficient filtration and regular water changes is crucial for their health.
Diet and Feeding
As herbivores, Oneknife Unicornfish primarily feed on algae in the wild. In captivity, their diet should consist of a variety of marine algae, seaweed, and high-quality herbivore pellets. Supplementing their diet with fresh vegetables like lettuce or spinach can also be beneficial.
Feeding should occur several times a day, providing only as much food as they can consume in a few minutes. This helps prevent overfeeding and maintains water quality.
Behavior and Compatibility
Oneknife Unicornfish are generally peaceful and can coexist with a variety of other reef-safe fish. However, they may exhibit territorial behavior towards conspecifics or other similar species, especially in smaller tanks. Providing ample space and hiding spots can help mitigate any aggression.
They are best kept in larger community tanks with other peaceful species. Avoid housing them with aggressive tank mates that might stress them or compete for food.
Health and Common Issues
With proper care, the Oneknife Unicornfish can live for many years in captivity. Regular monitoring of water parameters and maintaining a balanced diet are key to preventing common health issues such as ich or fin rot.
When selecting a Oneknife Unicornfish, look for active individuals with clear eyes and smooth skin. Avoid fish that appear lethargic or have visible signs of disease.
Habitat
Naso thynnoides is native to the warm, tropical waters of the Indo-Pacific region. It prefers coral-rich environments with plenty of algae to graze on. These fish are often found in schools, navigating the open waters of reefs and coastal lagoons.