Sea Apples in Reef Aquariums: Adding Colour and Intrigue to Your Underwater World
Reef aquariums are a captivating hobby for many marine enthusiasts, offering a glimpse into the vibrant and diverse ecosystems found in our oceans. Among the myriad of fascinating creatures that can be housed in a reef tank, the sea apple stands out due to its striking colours, unique appearance, and interesting behaviour. This long-form article will delve into the characteristics of sea apples, their natural habitats, and how to successfully keep them in a reef aquarium.
What Are Sea Apples?
Sea apples belong to the genus Pseudocolochirus and are a type of sea cucumber. They are echinoderms, closely related to sea stars and sea urchins. Sea apples are named for their vibrant, balloon-like bodies that often resemble the shape and colour of an apple. They are found in the Indo-Pacific region, particularly in areas with strong currents, where they can filter feed efficiently.
The most commonly kept species in aquariums are the Australian Sea Apple (Pseudocolochirus violaceus) and the Japanese Sea Apple (Pseudocolochirus axiologus). These species are known for their vivid coloration, with hues ranging from deep purples and blues to bright reds and yellows.
Why Keep Sea Apples in a Reef Aquarium?
Sea apples are a unique and eye-catching addition to a reef aquarium for several reasons:
1. Visual Appeal: Their bright colours and distinctive appearance make them a focal point in any tank.
2. Behaviour: Sea apples are filter feeders, extending their feathery tentacles to capture plankton from the water, providing a dynamic and mesmerising display.
3. Ecological Role: They contribute to the tank’s biodiversity and can help maintain water quality by filtering organic particles from the water column.
Setting Up the Ideal Environment
To successfully keep sea apples in a reef aquarium, it is essential to create an environment that meets their specific needs. Here are key considerations:
Tank Size and Setup
• Tank Size: A minimum tank size of 50 gallons is recommended for housing sea apples, as they require ample space for water movement and to prevent stress from crowding.
• Live Rock and Substrate: Incorporate plenty of live rock to provide stable surfaces for sea apples to anchor themselves. A sandy substrate is ideal for replicating their natural habitat.
Water Parameters
• Temperature: Maintain a stable temperature between 72-78°F.
• Salinity: Keep salinity levels between 1.023 and 1.025 specific gravity.
• pH: Ensure the pH is between 8.1 and 8.4.
• Nitrates and Phosphates: Regularly monitor and keep nitrates and phosphates at low levels to maintain optimal water quality.
Lighting
• Provide moderate to strong lighting to support the overall health of the tank and any photosynthetic corals present. While sea apples do not require specific lighting conditions, appropriate lighting can help maintain a balanced ecosystem.
Water Movement
• Sea apples thrive in areas with strong, consistent water movement, which helps them feed effectively. Use powerheads and wavemakers to create a flow that mimics their natural environment.
Feeding Sea Apples
Sea apples are suspension feeders, relying on plankton and other small organic particles in the water for sustenance. In a reef aquarium, their diet can be supplemented with:
• Phytoplankton: Commercially available liquid phytoplankton can be added to the tank to provide a steady food source.
• Rotifers and Copepods: These tiny zooplankton can also be introduced to the water column to enhance the feeding options for sea apples.
• Marine Snow: A mixture of tiny organic particles and microorganisms, marine snow is another excellent food source for sea apples.
It is crucial to maintain a consistent feeding regimen, as sea apples rely on a continuous supply of food to thrive. Regularly monitor their feeding behaviour to ensure they are capturing enough food.
Compatibility with Other Tank Inhabitants
When introducing sea apples to a reef tank, it is essential to consider their compatibility with other tank inhabitants:
Fish
• Safe Choices: Many reef-safe fish, such as clownfish, gobies, and tangs, coexist well with sea apples. These fish typically do not bother the sea apples and contribute to a balanced tank environment.
• Potential Issues: Avoid fish species that may nip at the sea apple’s tentacles, such as certain butterflyfish and angelfish.
Corals and Invertebrates
• Corals: Sea apples generally do not harm corals. Their filter feeding helps maintain water quality, indirectly benefiting coral health.
• Other Invertebrates: Sea apples can coexist with various invertebrates, such as snails, shrimp, and other non-aggressive crabs. Monitor interactions to ensure peaceful coexistence.
Behavioural and Ecological Observations
Sea apples exhibit a range of fascinating behaviours that can be observed in a reef tank setting. These behaviours include:
Filter Feeding
• Sea apples extend their feathery tentacles into the water column to capture plankton and other small particles. Watching them feed is a mesmerising sight, as their tentacles rhythmically move with the water flow.
Colour Changes
• Some sea apples can change colour slightly in response to environmental conditions or stress. This ability adds another layer of intrigue to observing their behaviour.
Anchoring and Movement
• Sea apples use their tube feet to anchor themselves to rocks or other surfaces. While they are generally sessile, they can move slowly if necessary, often in response to changes in water flow or food availability.
Challenges and Considerations
Keeping sea apples in a reef tank comes with challenges and considerations:
Sensitivity to Water Quality
• Water Quality: Sea apples are highly sensitive to water quality. Poor water conditions can cause stress, leading to the release of toxins. Regular water changes and monitoring are essential to maintaining optimal conditions.
Potential for Toxin Release
• Toxin Release: If stressed or injured, sea apples can release toxins that may harm other tank inhabitants. It is crucial to handle them with care and avoid situations that may cause stress, such as sudden changes in water parameters or aggressive tank mates.
Feeding Requirements
• Consistent Feeding: Ensuring a steady supply of plankton and other food sources is critical for the health of sea apples. An automatic feeder for phytoplankton or regular manual feeding can help maintain their nutritional needs.
Selecting the Right Sea Apple
When choosing a sea apple for your reef tank, consider the following species that are popular among aquarists:
Australian Sea Apple (Pseudocolochirus violaceus)
• Known for its vibrant purple and red coloration with yellow highlights.
• Prefers strong water flow and a well-established tank with stable water conditions.
Japanese Sea Apple (Pseudocolochirus axiologus)
• Features a mix of bright colours, including red, blue, and yellow.
• Requires similar care conditions to the Australian Sea Apple, with a focus on strong water movement and consistent feeding.
Each species has unique requirements and behaviours, so research and choose one that best fits your tank’s conditions and your level of experience.
