Harlequin Shrimp: The Stunning Starfish Hunters

Reef aquariums are home to a vast array of fascinating creatures, but few are as captivating and unique as the Harlequin Shrimp. Known for their striking appearance and specialised feeding habits, Harlequin Shrimp (Hymenocera elegans and Hymenocera picta) are a popular choice among advanced aquarists looking to add a touch of elegance and intrigue to their tanks.

This comprehensive guide will delve into the unique characteristics, feeding habits, and care requirements of Harlequin Shrimp, providing you with everything you need to know to successfully keep these stunning starfish hunters in your reef aquarium.

What Are Harlequin Shrimp?

Harlequin Shrimp are small, colourful crustaceans that inhabit the coral reefs of the Indo-Pacific region. They are easily recognisable by their ornate bodies adorned with bright, contrasting colours and intricate patterns. Their scientific name, Hymenocera, is derived from the Greek words for “membrane” and “horn,” referring to their distinctive flattened and horn-like appendages.

Unique Feeding Habits

Harlequin Shrimp are obligate predators of echinoderms, with a particular preference for starfish. Their specialised diet makes them both fascinating and challenging to keep in a reef aquarium.

1. Diet Specificity
• Harlequin Shrimp feed almost exclusively on starfish, including species such as Asterina, Linckia, and Fromia. They use their powerful claws to flip the starfish over and feed on the tube feet and soft tissues. This highly specialised diet means that a steady supply of starfish is essential for their survival in captivity.

2. Feeding Behaviour
• Harlequin Shrimp exhibit a unique and meticulous feeding behaviour. They immobilise the starfish by biting off its tube feet and then slowly consume it over several days. This process can take anywhere from a few days to a week, depending on the size of the starfish and the shrimp.

3. Starfish Preparation
• Some aquarists choose to pre-cut starfish into smaller pieces to make feeding easier and to control the amount of food available. However, it’s important to note that Harlequin Shrimp are natural hunters, and the act of catching and immobilising their prey is an essential part of their feeding behaviour.

Care Requirements in Reef Aquariums

Keeping Harlequin Shrimp in a reef aquarium requires careful attention to their specific needs and environmental conditions.

Tank Setup and Environment

1. Tank Size
• A minimum tank size of 20 gallons is recommended for a pair of Harlequin Shrimp. Larger tanks are preferable if you plan to keep multiple pairs or additional tank inhabitants.

2. Water Parameters
• Harlequin Shrimp require stable water conditions to thrive. Maintain a temperature range of 72-78°F, salinity levels of 1.023-1.025 specific gravity, and a pH of 8.1-8.4.

3. Substrate and Rockwork
• Provide a variety of live rock and crevices to mimic their natural habitat. Harlequin Shrimp are reclusive and appreciate plenty of hiding spots where they can retreat and feel secure.

Feeding and Nutrition

1. Starfish Supply
• Ensure a steady supply of appropriate starfish for feeding. It is crucial to research and source starfish that are safe and suitable for Harlequin Shrimp consumption. Asterina starfish are a common and convenient option for many aquarists.

2. Feeding Frequency
• Feed your Harlequin Shrimp a starfish every 1-2 weeks, depending on the size of the shrimp and the starfish. Monitor their feeding behaviour and adjust the frequency as needed to ensure they receive adequate nutrition.

3. Supplementation
• While Harlequin Shrimp primarily feed on starfish, occasional supplementation with other meaty foods such as chopped shrimp or fish can provide additional nutrients.

Compatibility with Other Tank Inhabitants

1. Fish
• Harlequin Shrimp are generally peaceful and can coexist with a variety of reef-safe fish. Avoid aggressive or predatory fish that may harm or stress the shrimp.

2. Invertebrates
• Harlequin Shrimp can be kept with other non-echinoderm invertebrates, such as cleaner shrimp, snails, and hermit crabs. Be cautious when introducing new invertebrates to ensure they do not compete for food or territory.

3. Corals
• Harlequin Shrimp are reef-safe and will not harm corals. Their striking appearance adds a vibrant touch to any coral display.

Challenges and Considerations

While Harlequin Shrimp are undeniably captivating, they come with several challenges and considerations that potential keepers should be aware of:

1. Specialised Diet
• The need for a constant supply of starfish can be challenging and costly. Ensure you have a reliable source of starfish before committing to keeping Harlequin Shrimp.

2. Sensitivity to Water Quality
• Harlequin Shrimp are sensitive to changes in water quality and require a well-maintained and stable environment. Regular monitoring and maintenance of water parameters are crucial for their health and well-being.

3. Short Lifespan
• Harlequin Shrimp have relatively short lifespans, typically ranging from 1 to 3 years. This natural life cycle requires careful planning and management to ensure their continued care and nutrition.

Breeding Harlequin Shrimp

Breeding Harlequin Shrimp in captivity is a challenging but rewarding endeavour. Successful breeding requires precise conditions and careful attention to the needs of the shrimp.

1. Pairing
• Harlequin Shrimp are usually found in pairs in the wild, and maintaining a bonded pair in captivity can increase the likelihood of breeding. Ensure you have a male and female pair, as Harlequin Shrimp are sexually dimorphic, with males typically being smaller than females.

2. Breeding Environment
• Provide a stable and stress-free environment with plenty of hiding spots and a consistent supply of starfish. Maintaining optimal water conditions is crucial for successful breeding.

3. Larval Rearing
• Raising Harlequin Shrimp larvae is a complex process that requires specialised knowledge and equipment. Larvae are planktonic and require specific planktonic food sources and careful management to ensure their survival.

Conclusion

Harlequin Shrimp are truly one of the most stunning and unique additions to a reef aquarium. Their vibrant colours, intricate patterns, and fascinating feeding behaviour make them a captivating subject for aquarists. However, their specialised diet and sensitivity to water conditions require careful planning and dedication.

By understanding their unique needs and providing the appropriate care, you can enjoy the beauty and intrigue of these remarkable starfish hunters in your reef tank. Whether you’re an experienced aquarist or looking to expand your knowledge, Harlequin Shrimp offer endless opportunities for observation and appreciation of the delicate balance of life within a reef ecosystem.