I've kept sun corals for over seven years, and I can tell you right now - these stunning orange and yellow polyps will completely change your approach to reef keeping. Unlike most corals in our tanks, sun corals (Tubastraea species) don't rely on photosynthesis for survival. This makes them both fascinating and challenging additions to any marine aquarium.
When I first brought home my orange sun coral colony, I made the classic mistake of treating it like my other LPS corals. Within two weeks, the polyps stopped opening, and I nearly lost the entire colony. That experience taught me everything about these unique non-photosynthetic corals, and today I manage multiple thriving colonies that feed eagerly every evening.
Sun corals belong to the family Dendrophylliidae and include several species commonly found in the aquarium trade. The most popular are Tubastraea coccinea (orange sun coral) and Tubastraea aurea (yellow sun coral). These large polyp stony corals (LPS) are azooxanthellate, meaning they lack the symbiotic algae that most corals depend on for nutrition.
What Is Sun Coral: Understanding Tubastraea Species
Sun corals are heterotrophic corals that capture prey from the water column to meet all their nutritional needs. Each polyp extends tentacles equipped with stinging cells called nematocysts to capture passing zooplankton, small fish, and other organic matter. This feeding behavior makes them completely different from the photosynthetic corals that dominate most reef tanks.
The genus Tubastraea contains approximately 16 recognized species, though recent research from the National Institutes of Health has identified three new species from Hong Kong waters. These corals form dense colonies with individual polyps ranging from 0.5 to 1.5 inches in diameter. When fully extended during feeding, a mature colony creates one of the most spectacular displays in marine aquariums.
What makes sun corals particularly interesting is their nocturnal nature. In their natural habitat, these corals remain closed during daylight hours and extend their polyps at night when zooplankton concentrations peak. This behavior persists in aquariums, though with consistent feeding schedules, you can train colonies to open during specific times regardless of lighting conditions.
The skeletal structure of sun corals consists of calcium carbonate, similar to other stony corals. However, their growth patterns differ significantly. Without zooxanthellae providing constant energy through photosynthesis, sun corals grow more slowly than their photosynthetic counterparts. A well-fed colony typically adds 2-3 new polyps per year under optimal conditions.
Natural Habitat and Distribution
Sun corals naturally inhabit shaded areas of tropical and subtropical reefs throughout the Indo-Pacific region. I've observed them in the wild during trips to Indonesia, where they colonize cave ceilings, overhangs, and the undersides of ledges - anywhere that receives minimal direct sunlight. These locations protect them from algae growth and position them perfectly to capture drifting prey.
Interestingly, several Tubastraea species have become successful invasive species outside their native range. The Smithsonian's NEMESIS database documents Tubastraea micranthus and T. coccinea populations throughout the Caribbean and Gulf of Mexico, where they've established themselves on oil platforms and artificial reefs. Their ability to thrive without sunlight gives them a competitive advantage in deeper waters and shaded structures.
According to NOAA Fisheries, one species, Tubastraea floreana, is listed as endangered due to its extremely limited range in the Galápagos Islands. This highlights the importance of responsible collection and aquaculture for the aquarium trade. Most sun corals available today come from sustainable sources in Indonesia and the Philippines, where collectors harvest small fragments that quickly regenerate on the parent colonies.
In their natural environment, sun corals face various predators including certain butterflyfish species, filefish, and crown-of-thorns starfish. Understanding these natural pressures helps explain their defensive behaviors and feeding strategies in our aquariums. When selecting reef tank companions, it's important to avoid species that might prey on your sun coral polyps.
Physical Characteristics and Identification
Identifying sun corals becomes straightforward once you know what to look for. The most distinctive feature is their tubular corallites - the skeletal cups that house individual polyps. These structures give the coral its scientific name, with "tuba" referring to the trumpet-like shape of each corallite. When I examine my colonies, I can see how each polyp sits protected within its calcium carbonate fortress.
Color variations in sun corals range from brilliant orange and yellow to deep red and even black in some rare species. The orange sun coral (T. coccinea) displays vibrant orange tissue with matching tentacles, while the yellow variety (T. aurea) shows golden hues that seem to glow under actinics. I've noticed that well-fed specimens maintain richer colors compared to struggling colonies.
The polyp structure itself consists of a central mouth surrounded by 24-36 tentacles arranged in cycles. Each tentacle contains thousands of nematocysts used for capturing prey. When fully extended, healthy polyps can reach 2-3 times their contracted size. During feeding, you'll observe tentacles actively moving and curling around captured food particles.
Growth patterns vary between species, but most form branching or encrusting colonies. New polyps bud from the base or sides of existing corallites, gradually expanding the colony's footprint. A mature colony can contain 50-100 individual polyps, creating an impressive display when all feed simultaneously. The skeleton beneath remains visible between polyps, often becoming colonized by coralline algae in established tanks.
Sun Coral Aquarium Care Requirements
Successfully keeping sun corals requires understanding their unique needs and committing to a regular feeding schedule. Unlike photosynthetic corals that can survive on light alone, these corals demand direct feeding multiple times per week. I feed my colonies 4-5 times weekly, and this consistency has resulted in excellent polyp extension and steady growth over the years.
Tank placement plays a crucial role in sun coral success. I position my colonies in lower flow areas where food can settle around the polyps during feeding. Caves, overhangs, or shaded spots work perfectly - locations that would kill most other corals. This placement also reduces algae growth on the skeleton, keeping the colony looking pristine.
Water quality requirements match those of other LPS corals, though sun corals show remarkable tolerance for less-than-perfect conditions. They thrive in standard reef parameters: temperature 76-82°F, salinity 1.024-1.026, pH 8.1-8.4, and alkalinity 8-11 dKH. However, I've found they handle slight parameter swings better than many SPS corals, likely due to their habitat in variable cave environments.
One critical aspect often overlooked is the importance of target feeding. Broadcasting food into the water column wastes resources and degrades water quality. Instead, I use a turkey baster or feeding syringe to deliver food directly to each polyp. This method ensures every polyp receives nutrition while minimizing excess nutrients in the system.
Feeding Sun Coral: Schedules and Techniques
Developing an effective feeding routine transformed my sun coral keeping experience. Initially, I struggled with inconsistent polyp extension and slow growth. Now, after years of refinement, my colonies respond eagerly to feeding time, with polyps extending within minutes of detecting food in the water.
The key to training sun corals lies in consistency. I feed at the same time each evening, typically 30 minutes after lights out. This schedule mimics their natural nocturnal feeding behavior while allowing me to observe the feeding response. Within two weeks of maintaining this routine, colonies learn to anticipate feeding and begin extending polyps at the scheduled time.
Food selection significantly impacts coral health and growth. My primary foods include enriched brine shrimp, mysis shrimp, and finely chopped seafood. I've found that variety promotes better polyp extension and coloration. Twice weekly, I add reef roids or similar coral foods to provide additional amino acids and trace elements. Each polyp can consume 2-3 adult brine shrimp per feeding, though appetite varies with colony size and health.
The feeding process itself requires patience and precision. First, I turn off flow pumps to prevent food from drifting away. Using a dedicated feeding syringe, I gently squirt food near each polyp cluster, watching as tentacles capture and transfer prey to the central mouth. The entire feeding takes 20-30 minutes for my three colonies. After feeding, I leave pumps off for another 15 minutes to allow complete ingestion before restoring flow.
Understanding feeding frequency helps balance coral nutrition with water quality. While daily feeding produces fastest growth, it also increases bioload significantly. I've settled on 4-5 feedings weekly as optimal for growth without compromising water parameters. During summer months when I travel, colonies tolerate weekly feeding for short periods, though growth slows noticeably.
Lighting Requirements and Placement Strategies
The non-photosynthetic nature of sun corals completely eliminates lighting requirements - a fact that surprises many reef keepers. In my tanks, sun corals thrive in areas receiving zero direct light. This unique characteristic opens up placement options unavailable for other corals. Under ledges, behind rock structures, or in dedicated cave systems all work perfectly.
While sun corals don't need light for survival, lighting affects their behavior patterns. Strong lighting triggers polyps to retract, protecting the soft tissue from potential UV damage and algae settlement. I've positioned my main colony beneath a rock overhang where it receives only indirect light. This placement keeps polyps more responsive during daytime feeding sessions.
Algae growth on sun coral skeletons presents a common challenge, particularly in well-lit tanks. Without zooxanthellae to compete for space, nuisance algae readily colonizes exposed skeleton. I combat this through strategic placement and maintaining a cleanup crew of hermit crabs and snails that graze around the colony base. Some aquarists use small powerheads to increase flow around colonies, preventing detritus accumulation that feeds algae growth.
Creating dedicated sun coral caves has become popular among serious keepers. I built my cave using marco rock, ensuring multiple entrance points for water flow while blocking direct light. Inside, I've mounted three sun coral colonies at different heights, creating a stunning display when all polyps extend during feeding. The cave design also simplifies target feeding since food naturally circulates within the structure.
Water Parameters and Tank Requirements
Maintaining stable water parameters ensures long-term sun coral success. Through years of testing, I've identified the optimal ranges that promote polyp extension and growth. Temperature stability proves especially important - fluctuations beyond 2°F daily can cause polyps to remain closed for days. I maintain 78°F year-round using a reliable heater controller.
Calcium and alkalinity levels directly impact skeletal growth. Sun corals grow slowly compared to photosynthetic species, but they still require adequate calcium (420-450 ppm) and alkalinity (8-10 dKH) for new polyp formation. I test these parameters weekly and dose accordingly. Magnesium levels around 1300-1400 ppm support proper calcium and alkalinity balance.
Nitrate and phosphate management becomes crucial with heavy feeding schedules. My sun coral tank runs slightly higher nutrients than typical SPS systems - nitrates 5-10 ppm and phosphates 0.03-0.08 ppm. These levels provide sufficient nutrients without promoting excessive algae growth. Regular water changes (15% weekly) help export excess nutrients while replenishing trace elements.
Flow patterns significantly affect feeding success and coral health. Sun corals prefer moderate, indirect flow that brings food particles without blasting polyps. I position powerheads to create gentle circulation around colonies, with stronger flow above to prevent detritus settlement. During feeding, I reduce flow to near-zero, allowing polyps to capture food efficiently. This flow management has dramatically improved feeding response and reduced food waste.
Tank size considerations often surprise newcomers to sun coral keeping. While individual colonies don't require massive tanks, the increased bioload from regular feeding demands robust filtration. I maintain my sun corals in a 75-gallon mixed reef with oversized protein skimming and biological filtration. Smaller tanks can work, but require more frequent maintenance and careful feeding portions.
Common Challenges and Troubleshooting
The most frequent issue I encounter with new sun coral keepers involves polyps refusing to open. This problem usually stems from inconsistent feeding schedules or poor water quality. When I acquired a struggling colony last year, polyps hadn't extended in weeks. Through patient conditioning with daily food offerings at the same time, polyps gradually began responding. Within a month, the colony fed as eagerly as my established ones.
Tissue recession represents another serious challenge that requires immediate attention. This condition typically begins at polyp bases and spreads upward, eventually killing affected polyps. In my experience, recession results from prolonged starvation or bacterial infections. I've successfully halted recession by increasing feeding frequency and treating with targeted coral dips. Early detection proves critical - once tissue loss exceeds 50%, recovery becomes unlikely.
Brown jelly disease occasionally affects stressed sun corals, appearing as a brown, gelatinous film over tissue. This bacterial infection spreads rapidly and can destroy entire colonies within days. When I spotted brown jelly on a new acquisition, I immediately removed affected polyps with bone cutters and dipped the remaining colony in iodine solution. Quick action saved most of the colony, though I lost four polyps to the infection.
Competition with faster-growing corals presents ongoing management challenges. Photosynthetic corals can quickly overgrow and shade sun coral colonies. I maintain clear boundaries around my sun corals, pruning neighboring colonies as needed. Some aquarists dedicate entire tanks to non-photosynthetic species, eliminating competition entirely. This approach simplifies care but requires commitment to the specialized feeding regime.
Pests and predators occasionally threaten sun coral colonies. Bristleworms sometimes irritate polyps, causing poor extension. While bristleworms generally benefit reef tanks by consuming detritus, excessive populations near sun corals create problems. I control bristleworm numbers through targeted removal and avoiding overfeeding. For specific aquarium terminology related to pest identification and treatment methods, understanding common abbreviations helps when researching solutions online.
Reproduction and Propagation
Sun corals reproduce both sexually and asexually in aquarium settings. Sexual reproduction occurs when colonies release planula larvae, typically triggered by temperature changes or lunar cycles. I've witnessed spawning events in my established colonies, with tiny orange larvae settling on nearby rocks. These larvae develop into new polyps over several weeks, though survival rates remain low without specialized rearing systems.
Asexual reproduction through budding provides the primary growth mechanism for sun coral colonies. New polyps form at the base of existing ones, gradually expanding the colony footprint. This process accelerates with consistent feeding - well-nourished colonies produce 3-5 new polyps annually. I've tracked individual colonies for years, documenting steady expansion from initial 10-polyp fragments to 50+ polyp showpieces.
Fragging sun corals requires different techniques than photosynthetic species. I use a Dremel with a diamond cutting wheel to separate polyp clusters, ensuring each fragment contains at least 3-4 connected polyps. Single polyps rarely survive fragging stress. After cutting, I mount fragments using underwater epoxy, positioning them in shaded areas with good flow. Recovery takes 2-3 weeks, with polyps gradually resuming normal feeding behavior.
Commercial propagation has increased sun coral availability while reducing wild collection pressure. Several aquaculture facilities now produce captive-bred colonies adapted to aquarium conditions. These specimens typically show better polyp extension and feeding response than wild-collected corals. When purchasing, I always ask about origin and choose aquacultured specimens when available.
Conservation Status and Environmental Impact
The conservation status of sun corals varies dramatically between species and locations. While some species like Tubastraea floreana face extinction threats in their native ranges, others have become problematic invasive species. This paradox highlights the complex relationship between marine ornamental trade and ecosystem conservation.
In the Atlantic and Caribbean, invasive sun coral populations threaten native coral communities. These non-native species compete for space on reef structures and lack natural predators to control their spread. Research from Brazil documents rapid sun coral expansion along the coastline, with some reefs showing 50% coverage by invasive Tubastraea species. Understanding this invasion helps aquarists appreciate the importance of responsible disposal - never release aquarium specimens into natural waters.
Sustainable collection practices have improved significantly over the past decade. Indonesian and Philippine collectors now use techniques that minimize reef damage, harvesting small fragments that allow parent colonies to regenerate. Many exporters participate in certification programs ensuring ethical collection and handling. When purchasing sun corals, I research suppliers and support those demonstrating commitment to sustainability.
Climate change impacts sun corals differently than photosynthetic species. Rising ocean temperatures don't cause bleaching in azooxanthellate corals, potentially giving them advantages as reefs warm. However, ocean acidification still affects their ability to build calcium carbonate skeletons. Some researchers suggest sun corals might play important roles in future reef communities as traditional coral species decline.
Integration with Other Non-Photosynthetic Species
Creating dedicated non-photosynthetic (NPS) systems has gained popularity among advanced aquarists. These specialized tanks focus entirely on corals that require direct feeding, including sun corals, dendronephthya, and certain gorgonians. I've experimented with mixed NPS systems and found sun corals pair excellently with other filter-feeding organisms.
Carnation corals make ideal tank mates for sun corals, sharing similar feeding requirements and placement preferences. Both species thrive in shaded areas with moderate flow and benefit from the same feeding regime. I maintain a 40-gallon NPS tank featuring orange sun corals alongside pink carnation corals, creating a stunning display of non-photosynthetic diversity.
Chili corals (Nephthyigorgia species) represent another compatible option for sun coral systems. These soft corals capture smaller particles than sun corals, utilizing different food sources within the same feeding session. This complementary feeding reduces waste and improves overall system efficiency. During feeding times, I observe both species extending simultaneously, creating spectacular polyp displays.
Sea pens, though rarely kept in home aquariums, can thrive alongside sun corals in specialized systems. These unique cnidarians require deep sand beds and gentle flow - conditions that also benefit sun coral colonies positioned near the substrate. Advanced keepers have successfully maintained diverse NPS communities by understanding each species' specific requirements while identifying commonalities in care.
Advanced Feeding Strategies and Automation
Automating sun coral feeding has revolutionized care for busy aquarists. I've installed a programmable dosing system that delivers liquid coral foods at preset times. While this doesn't replace target feeding entirely, it supplements nutrition between manual feeding sessions. The system activates after lights out, when polyps naturally extend, improving feeding efficiency.
Refrigerated food delivery systems represent the next level in feeding automation. These units maintain fresh or frozen foods at optimal temperatures, dispensing measured portions on schedule. I've tested several models and found them particularly useful during vacations. However, automated systems can't match the precision of manual target feeding, so I still hand-feed twice weekly for optimal results.
Training sun corals to feed during daylight hours simplifies maintenance for many keepers. Through consistent daytime feeding over several weeks, colonies adjust their behavior patterns. I've successfully trained one colony to extend polyps at 3 PM daily, coinciding with my afternoon maintenance routine. This flexibility proves especially valuable for aquarists who can't maintain evening feeding schedules.
Feeding stations concentrate food delivery and reduce waste in larger systems. I've created feeding zones using PVC pipe sections positioned above sun coral colonies. During feeding, I inject food into these tubes, allowing it to rain down directly onto waiting polyps. This method works particularly well in high-flow systems where broadcast feeding proves inefficient.
Frequently Asked Questions About Sun Coral Care
How often should I feed my sun coral?
Feed sun corals 3-5 times weekly for optimal growth and health. Daily feeding produces faster growth but increases bioload significantly. I've found 4 times weekly provides excellent results without compromising water quality. Consistency matters more than frequency - maintain whatever schedule you choose.
Why won't my sun coral polyps open?
Polyps typically remain closed due to inconsistent feeding, poor water quality, or excessive lighting. Start by checking parameters and ensuring stable conditions. Then establish a rigid feeding schedule at the same time daily. Most colonies begin responding within 2-3 weeks of consistent care. Patience and persistence usually solve extension issues.
Can sun corals survive without direct feeding?
No, sun corals cannot survive long-term without direct feeding. Unlike photosynthetic corals, they lack zooxanthellae and depend entirely on captured prey for nutrition. While they might survive briefly on dissolved organics, colonies gradually decline without regular feeding. I've rescued several starving colonies that recovered completely with proper nutrition.
Do sun corals need special lighting?
Sun corals require no lighting for survival and actually prefer shaded areas. Strong lighting can inhibit polyp extension and promote nuisance algae growth on their skeletons. I keep my colonies in caves or under overhangs where they receive minimal light. This placement encourages better polyp extension and reduces maintenance.
What's the best food for sun corals?
Enriched brine shrimp, mysis shrimp, and finely chopped seafood work excellently. I rotate between these foods, adding coral-specific supplements twice weekly. Each polyp can consume multiple brine shrimp per feeding. Variety ensures complete nutrition - don't rely on a single food source. Fresh or frozen foods generally produce better results than dried alternatives.
How do I propagate sun corals?
Use a Dremel or bone cutters to separate polyp clusters, ensuring each fragment contains 3-4 connected polyps. Mount fragments with underwater epoxy in shaded areas. Recovery takes 2-3 weeks before normal feeding resumes. I've successfully fragged dozens of colonies using this method, with survival rates exceeding 90% for multi-polyp fragments.
Are sun corals difficult for beginners?
Sun corals challenge beginners primarily due to feeding requirements rather than water parameter sensitivity. Success depends on commitment to regular feeding schedules. If you can dedicate time for feeding 3-4 times weekly, sun corals prove quite hardy. I recommend starting with a small colony to understand care requirements before expanding.
Can sun corals be kept with fish?
Yes, sun corals coexist well with most reef-safe fish. Avoid species known to pick at coral polyps like certain butterflies and filefish. I maintain sun corals with tangs, clownfish, and wrasses without issues. Fish actually benefit sun corals by stirring up detritus and small organisms that polyps can capture.
How fast do sun corals grow?
Growth rates depend entirely on feeding frequency and food quality. Well-fed colonies add 2-5 new polyps annually. I've documented colonies doubling in size over 3-4 years with consistent care. Compare this to photosynthetic corals that can show similar growth in months. Patience and dedication reward sun coral keepers with spectacular mature colonies.
What causes tissue recession in sun corals?
Tissue recession typically results from starvation, bacterial infections, or poor water quality. Address recession immediately by increasing feeding frequency and improving water conditions. I've saved colonies with early-stage recession through aggressive feeding and targeted coral dips. Prevention through consistent care proves easier than treating advanced recession.
Conclusion: Mastering Sun Coral Husbandry
After years of keeping sun corals, I can confidently say these non-photosynthetic beauties offer unique rewards for dedicated aquarists. Their vibrant colors, fascinating feeding behavior, and unusual care requirements set them apart from typical reef inhabitants. Success comes down to understanding their heterotrophic nature and committing to regular feeding schedules.
The transition from struggling novice to successful sun coral keeper taught me valuable lessons about marine biology and aquarium husbandry. These corals forced me to reconsider assumptions about coral care, especially regarding lighting and nutrition. Today, watching my colonies eagerly extend hundreds of polyps during feeding remains one of my favorite aquarium experiences.
For those considering sun corals, remember that success requires dedication rather than expertise. Start with a small colony to learn feeding techniques and observe behavioral patterns. Establish consistent routines and maintain stable water parameters. Within months, you'll develop the confidence to expand your collection and potentially explore other non-photosynthetic species.
Sun corals bridge the gap between traditional reef keeping and specialized systems. They introduce aquarists to the diverse world of heterotrophic organisms while remaining manageable for intermediate hobbyists. As more people succeed with these corals, we collectively improve husbandry techniques and reduce pressure on wild populations.
Looking ahead, sun coral keeping continues evolving with new automation technologies and improved understanding of their biology. Whether you're drawn to their beauty, interested in conservation, or seeking new challenges, sun corals offer remarkable opportunities. With patience, consistency, and proper care, these non-photosynthetic gems will reward you with years of stunning displays and fascinating behavior.
For additional coral care information and to expand your reef keeping knowledge, explore our guide on frogspawn coral care, another popular LPS species that makes an excellent addition to mixed reef systems. The techniques you master with sun corals will enhance your overall coral husbandry skills.
