Sinularia coral, often recognized as leather coral or finger leather coral, is a widespread genus of soft corals belonging to the Alcyoniidae family. These corals are popular choices for home aquariums due to their soft, flexible, and leathery texture. With over 160 described species, Sinularia corals are known for their resilience and adaptability, making them a suitable addition for many marine aquarium enthusiasts.
Identification and Natural Habitat
Sinularia corals exhibit a variety of forms, ranging from flat, cabbage-like structures to branching, tree-like, or even bulbous shapes with long, flowing appendages. Their colors include shades of light brown, green, and yellow, with some varieties displaying more vibrant neon greens or even pinks. The texture is soft and flexible, though some species have densely packed calcareous needles called sclerites, which can make their base feel firm or rough. These sclerites provide structural support to the coral’s tissues.
In their natural environment, Sinularia corals are found across the Indo-Pacific region, including areas like Fiji, Tonga, the Solomon Islands, and the Great Barrier Reef. They inhabit shallow reef areas, often on reef slopes, where they can form large, dominant colonies. These corals are adaptable to various light conditions, thriving in clear, brightly lit shallows but also found in murkier depths, sometimes exceeding 120 feet. They also prefer areas with moderate to strong water currents, which helps maintain their health and shape.
Aquarium Care Requirements
Maintaining water parameters is important for Sinularia corals in an aquarium.
Temperature: 75-80°F (24-27°C)
Salinity: 1.025-1.026 specific gravity (35 ppt)
pH: 8.1-8.4
Alkalinity: 8-12 dKH
Calcium: 380-420 ppm
Magnesium: 1200-1350 ppm
Nitrates: Below 5 ppm
Phosphates: Below 0.03 ppm (to prevent algae growth and support coral health)
Sinularia corals primarily rely on their symbiotic zooxanthellae for nutrition, requiring adequate lighting for photosynthesis. Moderate to high lighting levels are recommended, with a PAR (Photosynthetically Active Radiation) range of 50-150. A light spectrum that includes both blue and white light is beneficial to mimic natural reef conditions and promote coral growth and coloration. While they can adapt to lower light, optimal growth and vibrancy are seen under brighter conditions.
Moderate to strong water flow is also beneficial for Sinularia corals. Proper water movement helps prevent detritus from settling on the coral’s surface, which can lead to tissue damage, and ensures the delivery of essential nutrients and oxygen. While Sinularia primarily obtains nutrients from photosynthesis, they can benefit from supplemental feedings of planktonic foods such as phytoplankton or zooplankton, especially in lower light setups. Broadcast feeding, where food is dispersed into the water column, is a common method for these filter-feeding corals.
Growth and Propagation
Sinularia corals exhibit a moderate to fast growth rate, increasing several centimeters per month under favorable conditions. Their growth form can vary depending on water flow, with stronger currents leading to thicker, stubbier lobes and branches. These corals periodically retract their polyps and form a waxy film, a natural shedding mechanism to prevent nuisance algae from growing on their surface. This shrunken state can last for a couple of weeks before the film is shed and the polyps re-extend. Increased water circulation around the coral can assist in this shedding process.
Sinularia corals are readily propagated through fragmentation, a common method for hobbyists. This involves cutting a piece, or “frag,” from a mature coral colony using a sharp tool, such as stainless steel scissors or a razor blade, often at the base of a branch. After cutting, the frag should be placed in a separate container of tank water to minimize the release of any toxins into the main aquarium. Soft corals, including Sinularia, cannot be glued directly to a frag plug due to their slimy texture. Instead, they are attached to a new base, such as rubble rock or a coral plug, using a rubber band or a toothpick to hold them in place until they naturally adhere, which can take a few weeks.
Common Issues and Compatibility
Sinularia corals are considered hardy, but they can experience issues if water parameters are unstable or if they are exposed to stressors. One significant consideration is allelopathy, where Sinularia species release chemical compounds that are toxic to other corals. These exudates can inhibit or stunt the growth of more sensitive stony corals, even without direct physical contact. Running activated carbon in the aquarium can help adsorb these released toxins.
While Sinularia are resilient, they can still be susceptible to common coral pests and diseases. Flatworms can be observed on their surfaces, causing stress or reduced polyp extension. Bacterial infections can also occur, leading to tissue loss or discoloration. Maintaining stable water parameters and performing regular coral dips when introducing new specimens can help prevent the spread of pests and diseases.
When considering compatibility, Sinularia corals are peaceful with most non-aggressive fish and invertebrates. However, due to their potential for chemical warfare, provide ample space between Sinularia and other coral species, particularly stony corals, to avoid negative interactions. Some sources suggest they are best kept with other leather corals, zoanthids, and mushroom corals. Monitoring coral interactions and being prepared to reposition corals can help ensure a harmonious reef environment.