Common name: Whitemargin Unicornfish

General Information

The Whitemargin Unicornfish, scientifically known as Naso annulatus, is a captivating species notable for its distinctive appearance and robust size. Recognizable by its elongated body, prominent horn-like structure on the forehead, and the striking white margin that lines its tail, this fish is a standout addition to large marine aquariums. Despite its size, it is a peaceful species, making it a popular choice among aquarists with ample tank space.

In the wild, Naso annulatus is found in tropical reef environments across the Indo-Pacific region. Its adaptability to captivity and striking appearance make it a sought-after species for public aquariums and experienced hobbyists alike. However, its large size and specific care requirements mean it is less common in private collections compared to smaller, more manageable species.

Care

Caring for the Whitemargin Unicornfish requires a substantial commitment in terms of space and resources. These fish thrive in large, well-maintained aquariums with plenty of swimming space. A tank of at least 1,000 liters (260 gallons) is recommended to accommodate their active nature and potential growth.

The aquarium should be equipped with efficient filtration and maintained with stable water parameters to replicate their natural reef habitat. Live rock structures can provide both shelter and grazing surfaces, enriching their environment and supporting their natural behaviors.

Diet and Feeding

Naso annulatus is primarily herbivorous, feeding on a variety of algae in its natural habitat. In captivity, they should be provided with a diet rich in marine algae, supplemented with high-quality herbivore pellets and occasional offerings of mysis shrimp or other protein sources to ensure balanced nutrition.

Feeding should occur several times a day, with portions that the fish can consume within a few minutes. This frequent feeding schedule helps mimic their natural grazing behavior and supports their dietary needs.

Behavior and Compatibility

The Whitemargin Unicornfish is known for its peaceful demeanor, making it a compatible tank mate for a variety of other fish species. They are generally non-aggressive, though their large size and active swimming habits should be considered when choosing tank companions.

While Naso annulatus does not pose a toxicity risk, its size and potential dominance in the aquarium should be accounted for in community setups. They are best housed with other large, non-aggressive species in spacious environments.

Reproduction

Reproduction of the Whitemargin Unicornfish in captivity is rare and challenging due to their large size and specific breeding requirements. In the wild, they are known to form large spawning aggregations, releasing eggs and sperm into the water column.

Health and Common Issues

With proper care, Naso annulatus can live for several years in captivity. Maintaining water quality and providing a balanced diet are crucial to their health. Regular monitoring for signs of stress or illness, such as changes in appetite or behavior, can help prevent common health issues.

They are susceptible to typical marine diseases, including ich and bacterial infections. Quarantining new fish and maintaining optimal tank conditions can help mitigate these risks.

Habitat

Naso annulatus inhabits coral reefs and rocky areas in the Indo-Pacific, often at depths ranging from 2 to 100 meters. They prefer environments with abundant algae, which supports their herbivorous diet. In captivity, replicating these conditions with live rock and stable water parameters is essential for their well-being.