Sinularia (Sinularia spp.) is among the most readily available soft corals in the aquarium hobby and belongs to the Alcyoniidae family within the order Alcyonacea. Named "leather coral" or "leather coral" for their dried appearance, these corals come in various color morphs—white, cream, beige, and green. With a broad tolerance for light, water flow, and water quality parameters, they are beginner-friendly and propagate quickly, bringing natural movement and vitality to reef tanks.
The genus Sinularia encompasses hundreds of species with varying body morphologies—branching, lobed, and flattened types. The most commonly traded variety is the finger leather (digitiform) type, characterized by finger-like branches extending from a central stalk. The scleroprotein (sclerites) covering the surface feels relatively firm to the touch, and the coral will contract and round up during water changes or periods of stress.
Classification: Phylum Cnidaria → Class Anthozoa → Soft Coral
Alternative Names: Leather coral, finger leather coral
Photosynthetic: Yes (harbors zooxanthellae)
Water Flow: Medium to strong (gentle wave-like turbulent flow is ideal)
Difficulty Level: Easy to moderate
Optimal Water Parameters and Temperature
Sinularia falls into the category of corals with broad water parameter tolerance among LPS and soft corals, but maintaining stable conditions is key to long-term success.
| Parameter | Recommended Range |
|---|
| Temperature | 24–26°C |
| Salinity (Specific Gravity) | 1.025–1.026 |
| pH | 8.1–8.4 |
| Alkalinity (KH) | 7–10 dKH |
| Calcium | 380–450 mg/L |
| Magnesium | 1,250–1,350 mg/L |
| Nitrate (NO₃) | 0–20 mg/L |
| Phosphate (PO₄) | 0.03–0.10 mg/L |
Notably, nitrate levels that are too low tend to cause color fading. Rather than pursuing an ULNS (Ultra-Low Nutrient System), Sinularia often thrives better in systems with a few fish and moderate nutrient levels. Growth can stall in ultra-low-nutrient SPS-focused systems with zero nitrate.
Selecting the Right Lighting
Since Sinularia harbors zooxanthellae (zooxanthellae) and relies on photosynthesis, lighting is essential. However, unlike SPS corals (such as Acropora), they do not require extremely high light intensity and will grow adequately under moderate lighting (PAR 80–200 μmol/m²/s).
- LED Lights: Mid-range LEDs like Reefbreeders or AI Prime are sufficient. Full-spectrum options with blue, white, and UV components are ideal.
- Light Duration: 8–10 hours per day. Gradual ramp-up and ramp-down cycles improve polyp extension.
- Placement: Mid-water to lower portions of the aquarium are suitable. There is no need to place them in the high-light zones reserved for SPS corals.
Water Flow Configuration
"Swaying" water flow is the key. Sinularia's finger-like projections should gently wave and sway, promoting polyp extension and preventing detritus accumulation. Rather than a single strong current, multidirectional turbulent flow created by wavemakers or multiple powerheads is ideal.
- Recommended flow rate: 10–25× tank volume per hour (turbulent equivalent)
- Pump placement: Avoid directing strong flow directly at the coral, as this causes contraction. Apply flow from an oblique angle behind the coral instead.
- Controller functions: Random or pulse modes are recommended.
Placement and Layout
Sinularia grows rapidly and exhibits allelopathy (chemical interference) against neighboring corals. It secretes mucus and terpene-based chemical compounds that can stress adjacent corals, so maintain adequate distance from LPS and SPS colonies.
- Minimum Distance: At least 5–10 cm from other corals
- Ideal Location: Lower portions of the aquarium near rock surfaces or sandy areas
- Activated Carbon: Weekly replacement is effective for removing chemical compounds
- Protein Skimmer: Run a high-quality skimmer at full capacity
Feeding
While photosynthesis is the primary nutrition source for Sinularia, adding planktonic organisms or amino acid-based liquid foods once or twice weekly will accelerate growth. However, monitor the impact on water quality. Begin with minimal doses.
Recommended Foods:
- Rotifers or phytoplankton
- Amino acid-based coral foods (e.g., Polyp-Lab Reef-Roids or Two Little Fishes Phytoplex)
- Small amounts of brine shrimp
Target feeding by pausing the powerheads and using a syringe to deliver food near the base of the coral is most effective.
Propagation (Fragging)
Sinularia is extremely easy to propagate through fragging (fragmentation). Healthy colonies recover quickly from cuts, and both the parent and fragments will regrow within weeks.
Steps:
1. Use a scalpel or scissors to cut off finger-like projections 2–5 cm in length
2. Secure the cut surface to a frag tile or live rock using reef-safe adhesive (Reef Glue)
3. Keep water flow gentle for 48 hours after attachment for stability
4. The sclerites will harden and the fragment will attach within 1–2 weeks
Important Note: Fragging triggers massive mucus secretion (terpene release). Either add activated carbon or perform increased water changes following fragging to prevent water quality degradation.
Common Problems and Solutions
Persistent contraction or withdrawal
→ Usually due to excessive water flow, prolonged lighting, or nitrate levels too low. First, reduce water flow and observe.
Excessive slimy mucus secretion
→ A stress response. Address with water changes and activated carbon replacement. Most recovery naturally within a few days.
Polyps remain closed
→ Common causes include insufficient acclimation, insufficient lighting duration, or excessively high nitrate (above 20 mg/L).
Partial bleaching or tissue decay (RTN-like)
→ While RTN is primarily an SPS phenomenon, localized tissue necrosis can occur in Sinularia. Remove affected sections promptly and relocate healthy portions to a separate tank or lower-flow area.
Neighboring corals are contracting
→ Possible allelopathy. Move Sinularia to a rock edge or separate area of the tank and increase activated carbon use.
Tips for Purchasing from Breeders
When purchasing Sinularia from a breeder-direct marketplace like br-choku, verify the following:
- Frag Attachment: Is the frag securely attached to the tile or live rock?
- Polyp Extension: Select individuals with extended polyps in the photos
- Shipping History: Confirm short-distance shipping and proper packing methods
- Color and Form: Enjoy selecting your preferred morph. White-green, cream, and green varieties offer diverse options
Summary
Sinularia is a soft coral that checks all the boxes: "easy to maintain, easy to propagate, and visually striking." By maintaining stable conditions with moderate water flow, medium lighting, and nitrate levels below 10 mg/L, even beginners can enjoy long-term success. As long as allelopathy management (activated carbon and spacing) is not neglected, Sinularia will become a dependable addition to your reef layout, bringing natural movement and richness to your aquascape.
