Sea Anemones and Zoanthids

Sea anemones and Zoanthids are among the most popular and colourful marine invertebrates in reef aquariums. Valued for their incredible variety of shapes, sizes and colours, they can create spectacular displays in both small and large reef tanks. Both belong to the Anthozoa class and require suitable water conditions, lighting and water flow to thrive in a marine aquarium.

With the right care, these fascinating reef animals can grow and develop vibrant colours, making them a popular choice among marine aquarium enthusiasts.

Types of sea anemones and Zoanthids for reef aquariums

There are many species and varieties of sea anemones and Zoanthids, each with its own appearance and care requirements. Depending on the species, they can be kept in everything from nano reef aquariums to large marine reef tanks.

Sea anemones

A sea anemone is a marine invertebrate that is usually solitary, although some species can form colonies. Sea anemones have a central mouth surrounded by stinging tentacles, which they use both for defence and to capture food.

Their size, shape and appearance vary considerably between species and genera. Some sea anemones form a symbiotic relationship with clownfish, creating one of the most iconic and fascinating interactions found in a reef aquarium.

Sea anemones can reproduce sexually or asexually, with some species reproducing through fission to create new individuals.

For a nano reef aquarium or small marine tank, Zoanthids are generally a more suitable option. Even anemones that are small when introduced can grow considerably and move around the aquarium in search of suitable conditions. In a confined space, this can pose a risk to nearby corals and other reef inhabitants.

Zoanthids

Zoanthids are colonial marine invertebrates belonging to the Zoanthidae family. They consist of individual polyps that grow together to form dense, colourful colonies. Their remarkable range of colours can include fluorescent green, orange, red, blue and purple.

Closely related to Palythoa, Zoanthids spread across rockwork and can gradually form impressive colonies. Their spectacular colours and relatively straightforward care requirements make Zoanthids for reef aquariums particularly popular, including with beginner reef keepers.

Zoanthid growth and coloration depend largely on water quality, lighting and water flow. Under suitable conditions, they can spread across live rock and develop into dense, colourful colonies. Their relatively compact size also makes many Zoanthids suitable for nano reef tanks as well as larger reef aquariums.

Sea anemone and Zoanthid care

Successful sea anemone and Zoanthid care depends on stable water parameters and good overall reef aquarium water quality. Lighting, water flow and placement should always be adapted to the requirements of the individual species.

• Water quality: A reef aquarium should have stable water parameters, with nitrate and phosphate levels kept low and under control. Excess nutrients can encourage unwanted algae growth and negatively affect the health of anemones, Zoanthids and other reef inhabitants.
• Lighting: Appropriate reef aquarium lighting is essential for anemones and Zoanthids that contain zooxanthellae, the symbiotic algae living within their tissues. Through photosynthesis, these algae provide their host with an important source of energy.
• Water flow: Moderate water flow helps carry food towards the polyps and tentacles while preventing waste from accumulating. The ideal flow will vary depending on the species.
• Placement: The best position in the aquarium depends on the species, its lighting requirements and its potential adult size. Zoanthids generally thrive in the lower to middle areas of a reef aquarium, depending on the intensity of the lighting. Moderate lighting can encourage healthy growth while helping them develop their characteristic vibrant colours.

Sea anemones require more space because many species can move around the aquarium until they find an area with suitable lighting and water flow.

Feeding sea anemones and Zoanthids

Many sea anemones and Zoanthids obtain part of their energy from the zooxanthellae living within their tissues. However, feeding sea anemones and Zoanthids can provide additional nutrients and help support healthy growth.

In a reef aquarium, they can capture zooplankton and suspended food particles from the water column. Depending on the species and the size of the polyps or anemone, they may also accept suitable marine pellets or thawed Artemia (brine shrimp).

Food should always be adapted to the species, size and feeding behaviour of the animal. Combined with stable water parameters, suitable lighting and appropriate water flow, a varied diet helps promote healthy growth, vibrant coloration and well-developed Zoanthid colonies.