Hologymnosus annulatus

Datasheet

General Description

Hologymnosus annulatus, commonly known as the Ring wrasse, is a species belonging to the Labridae family. These fish are known for their activity and relatively large size, requiring ample space in an aquarium setting. Often found in reef environments, they play a crucial role in controlling populations of unwanted invertebrates such as flatworms and pyramid snails. H. annulatus feeds on a variety of invertebrates and small fish, typically swallowing them whole or occasionally smashing them against rocks to break them into smaller pieces. They exhibit a unique behavior of burying themselves in the sand when threatened or resting, necessitating a deep substrate in aquariums for their well-being.

Aquarium Suitability

Hologymnosus annulatus is considered suitable for aquarium life but demands careful attention due to their specific needs and behaviors. They are best housed in a large aquarium with plenty of open space for swimming, as they are active and fast growers when adequately fed. However, they present challenges such as potentially preying on small fish, jumping out of open tanks, rearranging tank decor to forage for food, and showing aggression towards snails and crustaceans. These fish require attentive care during transport and acclimatization to minimize stress and potential injuries.

Demands, Care and Hardiness

With an average hardiness level, H. annulatus requires stable water parameters within a temperature range of 22.2-25.6°C and pH of 8.1-8.4. They thrive in aquariums with a specific gravity of 1.020-1.025 and carbonate hardness (KH) between 8-12. Additionally, these fish exhibit a mostly peaceful temperament but may display aggression towards similar species, emphasizing the importance of adequate space and hiding spots to reduce territorial behavior.

Reef Suitability

Considered reef safe with caution, Hologymnosus annulatus can be housed in reef aquariums but must be monitored closely for any potential interactions with coral species. Their feeding habits and tendency to rearrange rocks in search of food may pose a risk to delicate coral structures within the tank.

Aquarium Setup

Ideal aquarium setup for H. annulatus includes a large tank with a minimum capacity of 1500 liters, providing ample swimming space. A deep sandy substrate of at least 5 cm is necessary to accommodate their burrowing behavior and ensure their well-being. The presence of rocks and caves in the tank offers hiding spots and adds to their natural habitat, while maintaining water quality through efficient filtration and regular water changes is crucial for their health.

Behaviour

Ring wrasses are known for their active nature and fast growth rate when adequately nourished. They exhibit unique behaviors such as burying themselves in sand when feeling threatened or resting, as well as rearranging tank decor to explore and hunt for food. Additionally, they may display territorial aggression towards similar species, highlighting the need for careful observation and adequate space in a multi-fish aquarium setup.

Feeding and Diet

Hologymnosus annulatus has a varied diet that includes fish, larger crustaceans like shrimp and crabs, other invertebrates, and small crustaceans such as krill, mysis, and artemia. They are voracious eaters that consume prey whole or may break it down into smaller pieces by smashing it against rocks. Providing a diverse and well-rounded diet is essential for their nutritional needs and overall health.

Dimorphism

Hologymnosus annulatus exhibits hermaphroditic behavior, where females can change sex to become males when the need arises. This unique characteristic allows for flexibility in gender roles within a group of these fish and plays a role in their reproductive strategies.

Habitat and Distribution

Native to the Indo-Pacific region, Hologymnosus annulatus is found in areas ranging from the Red Sea and South Africa to the Society and Pitcairn Islands. Their habitat includes coral reefs and rocky outcrops, where they can forage for food and seek shelter. Understanding their natural distribution and habitat preferences is essential for creating a suitable environment in captivity that mimics their wild surroundings.