Soft Coral Guide: The Complete Care Guide for Reef
Quick Summary
Soft corals are the most forgiving and beginner-friendly group of reef corals. Unlike SPS and LPS, soft corals do not build rigid calcium carbonate skeletons. Instead, they support themselves with a flexible internal structure of spicules (tiny calcite needles embedded in their tissue). This makes them pliable, fast-growing, and remarkably resilient to the kinds of parameter fluctuations that damage stony corals.
Most soft corals thrive under low to moderate lighting (50 to 150 PAR), gentle to moderate flow, and the standard reef water chemistry you are already maintaining for fish. They tolerate wider parameter ranges than any stony coral category, making them the natural first step into coral keeping. If your reef tank has been cycled for at least 2 to 3 months and water parameters are reasonably stable, you are ready for soft corals.
What Makes Soft Corals Different
If you have ever held a piece of live rock with a Toadstool leather attached or watched Xenia pulse rhythmically in your tank, you have experienced the unique character of soft corals. They feel and behave differently from stony corals in almost every way.
The absence of a rigid skeleton is the fundamental distinction. Stony corals (SPS and LPS) invest enormous energy into building calcium carbonate structures. Soft corals redirect that energy into tissue growth, reproduction, and chemical defense. This is why soft corals grow faster, reproduce more readily, and recover from damage more quickly than most stony species.
Soft corals also rely less on their symbiotic zooxanthellae than SPS do. Many soft coral species supplement photosynthesis with direct particle feeding, dissolved organic absorption, or both. This reduced light dependence means they thrive in conditions that would starve demanding SPS corals.
The tradeoff is that soft corals lack the structural drama of stony coral skeletons. They do not build the intricate branches of Acropora or the massive domes of brain corals. Their beauty comes from movement, texture, and color rather than architectural form. For many reef keepers, the flowing, organic appearance of soft corals is exactly what they want.
Water Parameters for Soft Corals
Soft corals accept the widest parameter ranges of any coral group. This does not mean they are indifferent to water quality, but it does mean that the precision required for SPS is unnecessary.
Alkalinity
Acceptable range: 7.0 to 12.0 dKH. Soft corals do not build calcium carbonate skeletons, so they consume negligible alkalinity. In a soft-coral-only system, alkalinity remains remarkably stable between water changes because nothing is drawing it down.
Stability is still preferred. Sudden swings can stress any organism, but soft corals tolerate daily variation of 1.5 to 2.0 dKH without visible consequences. This is roughly three to four times the acceptable swing for SPS.
Calcium and Magnesium
Calcium: 350 to 450 ppm. Magnesium: 1,200 to 1,400 ppm. Soft corals use small amounts of calcium for their internal spicules but nowhere near the volume that stony corals consume. In most soft-coral systems, calcium and magnesium stay within range through regular water changes alone, without dedicated dosing.
Nitrate
Acceptable range: 2 to 30 ppm. Soft corals tolerate and often benefit from higher nutrient levels than stony corals. Many species grow fastest in nutrient-rich environments that would cause SPS to brown out and LPS to struggle. A community reef with a moderate fish load producing 10 to 20 ppm nitrate between water changes is an excellent environment for soft corals.
In practice, this makes soft corals ideal for tanks where maintaining ultra-low nutrients is impractical or undesirable. Fish-heavy community reefs, newer systems still stabilizing, and tanks without aggressive nutrient export all support soft corals well.
Phosphate
Acceptable range: 0.02 to 0.20 ppm. Soft corals tolerate significantly higher phosphate than stony corals. Elevated phosphate that would inhibit SPS calcification has minimal impact on soft coral growth. Keep phosphate below 0.25 ppm to prevent nuisance algae issues on rockwork, but do not chase the low levels that SPS demand.
Temperature
Target: 75 to 80°F (24 to 27°C). Soft corals handle temperature swings of 3 to 4°F better than stony corals, though consistent temperature is always preferable. A basic heater with a thermostat is sufficient for most soft-coral setups.
Salinity
Target: 1.023 to 1.026 specific gravity. Soft corals accept a slightly wider salinity range than stony corals. An auto top-off system for evaporation is still recommended, but brief salinity variations from missed top-offs are less consequential than they would be with SPS.
Lighting for Soft Corals
Soft corals have the lowest light requirements of any photosynthetic coral group. This is one of their greatest practical advantages, as it reduces equipment costs and simplifies the lighting setup.
PAR Requirements
Most soft corals thrive at PAR levels of 50 to 150 at their placement point. Some species-specific ranges:
- Very low light tolerant (30 to 75 PAR): Green Star Polyps, Clove Polyps, some Sinularia
- Low to moderate (50 to 125 PAR): Toadstool Leather, Kenya Tree, Colt Coral, Xenia
- Moderate (75 to 175 PAR): Zoanthids, Palythoa, Mushrooms (Discosoma, Rhodactis, Ricordea)
Excessive light causes soft corals to retract, shed mucus, or develop bleached patches. If you notice a soft coral that was thriving suddenly retracting and refusing to open, and your water parameters have not changed, excess light is a likely cause. This is especially common when soft corals are placed too high in a tank designed for SPS lighting levels.
Spectrum
Soft corals respond well to blue-heavy spectrums, which enhance their fluorescent coloration. Many zoanthids and mushroom corals exhibit dramatically different (and often more vivid) colors under actinic or blue LED lighting compared to full white.
A standard reef LED fixture running a blue-weighted spectrum works perfectly. There is no need for specialized lighting. If you are running a mixed reef with SPS at the top, the light that reaches the lower zones where soft corals sit is typically in the ideal range already.
Photoperiod
Run lights for 8 to 10 hours daily. Soft corals are less sensitive to photoperiod than SPS, but a consistent schedule helps maintain overall tank stability and prevents algae issues from excessive lighting duration.
Flow for Soft Corals
Soft corals generally prefer gentle to moderate water movement. Their flexible bodies sway with the current, and moderate flow keeps waste from settling on their tissue while allowing polyps to extend and feed.
How Much Flow
Total flow of 10 to 20 times tank volume per hour from all sources suits most soft coral setups. This is lower than what SPS systems require and similar to or slightly less than LPS recommendations.
Flow Preferences by Species
Different soft corals respond to flow differently, and matching their placement to flow intensity produces the best polyp extension and growth.
Toadstool Leathers and Sinularia prefer moderate flow. Their broad surface area needs enough current to clear mucus (a natural cleaning behavior) and prevent detritus buildup, but direct strong current causes the polyps to retract permanently.
Xenia and Clove Polyps prefer gentle flow. These delicate pulsing corals do best in sheltered areas with indirect water movement. Strong current inhibits their characteristic pulsing behavior and can cause tissue damage.
Zoanthids and Mushrooms tolerate a wide range from gentle to moderate. They are among the most adaptable soft corals for flow. If polyps are not fully opening, try reducing flow in their area before adjusting other variables.
Green Star Polyps (GSP) are unusually tolerant of moderate to moderately strong flow. They thrive on surfaces where other soft corals might struggle, including areas near filter returns or wavemaker output.
Feeding Soft Corals
Soft corals are less dependent on direct feeding than LPS, but supplemental nutrition still improves their health and growth.
Photosynthesis
Most soft corals derive the majority of their energy from their symbiotic zooxanthellae. Under appropriate lighting, photosynthesis alone sustains basic tissue maintenance and moderate growth. This is why soft corals survive in tanks where no one target-feeds them.
Broadcast Feeding
Phytoplankton and fine particulate coral foods benefit soft corals when broadcast into the water column. Dose 1 to 2 times per week. The small polyps of soft corals capture fine particles from the water as it flows past.
Amino acid supplements also benefit soft corals, supporting tissue health and coloration. These are the same products used for SPS feeding and provide background nutrition that photosynthesis alone does not fully supply.
Target Feeding
Some soft corals accept direct feeding. Mushroom corals (especially larger Rhodactis and Ricordea) can consume small pieces of mysis shrimp placed directly on the disc. Zoanthids and Palythoa accept fine particulate foods placed near their polyps. Most leathers and Xenia do not respond to target feeding and rely on photosynthesis and dissolved organics.
Fish Waste as Nutrition
In tanks with a healthy fish population, dissolved and particulate organic waste provides significant nutrition to soft corals. This is why soft corals often grow fastest in fish-heavy community tanks where nutrient levels are naturally elevated. The fish waste creates a constant supply of dissolved organics and fine particles that soft corals absorb passively.
Common Soft Coral Species
Each soft coral genus has distinct characteristics. Understanding these helps you choose species that match your system and aesthetic preferences.
Toadstool Leather (Sarcophyton)
One of the most iconic soft corals. Toadstool Leathers grow as a thick stalk topped by a broad, flat cap covered in short polyps. When extended, the polyps give the surface a fuzzy, textured appearance. When retracted, the cap looks smooth and leathery.
Toadstools periodically shed a waxy mucus layer as a natural cleaning process. The coral retracts all polyps, produces a clear film over its surface, and after 1 to 3 days sheds the film and re-extends. This is normal behavior and not a sign of stress. You will often notice new reef keepers worrying about this cycle. It happens every few weeks and is completely healthy.
Toadstools grow large. A small frag can become a 15 to 20 cm specimen within a year. Plan placement accordingly and be prepared to frag if it outgrows its space.
Care: low to moderate light (75 to 150 PAR), moderate flow, minimal feeding needed. One of the hardiest corals available.
Kenya Tree (Capnella)
Fast-growing, tree-shaped soft coral that branches and drops small fragments that attach and grow independently. Kenya Trees are among the easiest corals to propagate, often self-fragging by dropping branchlets that attach to nearby surfaces.
This self-propagation can become invasive. In established tanks, Kenya Tree fragments can colonize rockwork across the entire tank if not managed. Some reef keepers love this; others consider it a nuisance. Be aware of this tendency before adding one to your tank.
Care: low to moderate light (50 to 125 PAR), gentle to moderate flow, no feeding needed.
Pulsing Xenia
Xenia is unique in the coral world for its rhythmic pulsing behavior. The polyps open and close in a hypnotic pattern that is one of the most visually distinctive displays in any reef tank.
Like Kenya Trees, Xenia can be invasive. It spreads rapidly across rockwork and is difficult to remove once established because it regrows from tiny tissue fragments. Many experienced reef keepers place Xenia on isolated rock islands that do not connect to the main rockwork, preventing it from spreading into areas where it is not wanted.
Xenia is also unusual in that it sometimes mysteriously crashes (dies off completely) in established tanks without obvious cause. The mechanisms behind these crashes are not fully understood. This unpredictability is accepted in the hobby as part of keeping Xenia.
Care: low light (50 to 100 PAR), gentle flow, no feeding needed.
Zoanthids and Palythoa
Zoanthids (Zoas) are the collectible corals of the reef hobby. They grow as mats of small polyps in an extraordinary range of colors and patterns, with rare morphs commanding premium prices. Palythoa are closely related but have larger, more uniform polyps.
Both are hardy and grow readily under a wide range of conditions. They tolerate low to moderate light (50 to 175 PAR) and gentle to moderate flow. They respond to broadcast feeding and show accelerated growth when nutrient levels are moderate.
Safety warning: Palythoa (and some Zoanthid species) contain palytoxin, one of the most potent biological toxins known. Palytoxin is dangerous if it contacts broken skin, eyes, or is inhaled as aerosol (such as when fragging near boiling water or steam). Always handle Palythoa and Zoanthids with gloves, work in a well-ventilated area, and never boil or heat rock with these corals attached.
Mushroom Corals (Discosoma, Rhodactis, Ricordea)
Mushroom corals are disc-shaped soft corals that sit flat on rockwork or substrate. They come in a wide range of colors (blue, green, red, spotted, striped) and vary in size from 2 cm (Discosoma) to over 15 cm (Rhodactis).
Mushrooms are among the lowest-maintenance corals in the hobby. They tolerate very low light (30 to 100 PAR), gentle flow, and high nutrient levels. They reproduce by splitting or dropping small tissue fragments that grow into new individuals.
Ricordea (both R. florida and R. yuma) are the premium mushroom varieties. They produce vivid, multi-colored specimens and command higher prices. R. yuma is slightly more demanding than Discosoma, preferring moderate light and cleaner water. R. florida is hardier and more adaptable.
Care: very low to moderate light, gentle flow, optional target feeding for larger specimens.
Green Star Polyps (GSP)
A mat-forming soft coral with bright green polyps that extend from a purple encrusting base. GSP grows rapidly and will cover rockwork, back walls, and overflow boxes if given the opportunity.
Many reef keepers deliberately grow GSP on the back glass or overflow box as a living green wall. Others find it invasive when it spreads onto rockwork where it competes with other corals for space.
Care: low to moderate light (50 to 150 PAR), moderate flow, no feeding needed. One of the hardiest and fastest-growing corals available.
Colt Coral (Cladiella)
A branching soft coral with thick, fleshy branches that look like a cauliflower or small tree. Colt Corals grow quickly and can be pruned by simply cutting branches with scissors. The cut heals within days.
Care: low to moderate light (75 to 125 PAR), moderate flow, minimal feeding.
Chemical Warfare: Allelopathy
Soft corals are prolific chemical warriors. This is one of the most important and least understood aspects of keeping them in mixed reef systems.
What Is Allelopathy?
Many soft corals release chemical compounds (terpenes and other organic molecules) into the water that inhibit the growth of competing corals. This chemical warfare, called allelopathy, is a natural defense mechanism that helps soft corals compete for space on crowded reefs.
In the open ocean, dilution and water volume minimize the impact. In the closed system of a reef tank, these chemicals concentrate and can reach levels that stress or damage stony corals.
Which Soft Corals Are Most Allelopathic?
Leather corals (Sarcophyton, Sinularia, Lobophytum) are the most potent producers of allelopathic compounds. Their large tissue mass releases significant quantities of terpenes, particularly during mucus shedding events. Xenia and Kenya Trees are less allelopathic but still produce some chemical output.
Zoanthids, mushrooms, and GSP are generally low allelopathic producers, making them safer choices for mixed reef tanks.
Managing Allelopathy
If you keep soft corals alongside SPS or sensitive LPS, take these steps to manage chemical warfare:
- Run activated carbon continuously. Carbon adsorbs many allelopathic compounds from the water. Replace carbon every 2 to 4 weeks.
- Run a protein skimmer. Skimming removes dissolved organics including allelopathic chemicals.
- Maintain regular water changes. Weekly 10 to 15 percent water changes dilute accumulated chemical compounds.
- Provide distance. Place allelopathic soft corals (leathers especially) as far as practical from sensitive stony corals.
In soft-coral-only tanks, allelopathy is not a concern because the soft corals tolerate each other's chemical output. It becomes significant only in mixed reef systems where stony corals are present.
Propagation
Soft corals are the easiest group to propagate, and fragging is one of the most rewarding aspects of keeping them.
Cutting Frags
Most soft corals can be fragged with a sharp razor blade or scissors. Cut a branch, polyp cluster, or section of the parent colony and attach it to a frag plug or rubble rock with superglue gel or a rubber band. The tissue heals within days and begins growing from the cut surface.
Leather corals tolerate aggressive fragging. You can slice Toadstool caps into multiple pieces, and each piece will develop into a complete new colony. Kenya Trees can be snapped by hand. GSP can be peeled off surfaces in sections and re-attached elsewhere.
Natural Propagation
Many soft corals propagate themselves without intervention. Kenya Trees drop branchlets. Xenia spreads across connected surfaces. Mushrooms split spontaneously. GSP encrusts outward from its margins. In established tanks, these species often need management (removing unwanted growth) rather than deliberate propagation.
Common Problems
Soft corals are resilient, but they do experience problems. Most are mild and self-resolving.
Persistent Retraction
When soft coral polyps stay retracted for more than 2 to 3 days, something in the environment is wrong. Common causes: excessive light, excessive flow, water chemistry change, allelopathic stress from a newly added coral, or contamination (copper from medications, household chemicals from aerosol sprays near the tank).
Check parameters, review recent changes to the tank, and test for contamination. In most cases, correcting the environmental issue prompts re-extension within days.
Mucus Shedding (Leathers)
Toadstool Leathers and other Sarcophyton species periodically coat themselves in a waxy mucus film and retract all polyps. This cycle lasts 1 to 3 days and is a normal self-cleaning behavior. No intervention is needed. Moderate flow helps the coral shed the mucus layer.
If mucus shedding lasts more than 5 days or recurs very frequently (more than weekly), the coral may be stressed by poor water quality or persistent irritation. Test parameters and evaluate flow and light in the coral's position.
Tissue Recession or Melting
Soft coral tissue that turns translucent, mushy, or begins dissolving indicates serious stress. Common causes: severe water chemistry problems (ammonia spike, extreme salinity shift), bacterial infection following physical damage, or prolonged exposure to concentrated allelopathic chemicals.
Remove the affected coral and place it in a quarantine container with stable, clean water. Remove any visibly dead tissue. If healthy tissue remains, the coral may recover over 1 to 2 weeks in quarantine.
Invasive Growth
Some soft corals (Xenia, GSP, Kenya Tree) grow so aggressively that they overtake rockwork and compete with other corals for space. Prevention is easier than removal. Place invasive species on isolated rock islands not connected to the main structure. Prune regularly. Remove any fragments that appear on unwanted surfaces before they attach.
Advanced: Soft Corals in the Mixed Reef
Integrating soft corals into a mixed reef with LPS and SPS requires balancing their chemical output against the sensitivity of stony corals.
The most successful mixed reefs use activated carbon and protein skimming as standard equipment (which most reef tanks already run) and choose soft coral species with lower allelopathic profiles. Zoanthids, mushrooms, and GSP coexist well with stony corals. Leather corals are the highest-risk additions to mixed systems due to their potent terpene production.
Placement strategy matters. Keep leathers on opposite ends of the tank from your most sensitive SPS. Use natural flow patterns to carry allelopathic compounds toward the overflow or skimmer rather than across stony coral colonies. Run carbon consistently and replace it on schedule.
Many successful mixed reef tanks contain leather corals alongside thriving SPS. The key is not avoiding soft corals entirely but managing their chemical output through filtration and strategic placement.
Advanced: Why Soft Corals Crash
Xenia and occasionally other soft corals experience sudden, catastrophic colony death in tanks where they were previously thriving. These crashes are one of the genuine mysteries of reef keeping.
Theories include shifts in trace element composition, accumulation of their own allelopathic compounds reaching toxic concentrations in a closed system, bacterial infection triggered by a subtle parameter change, or reproductive exhaustion (the colony invests everything in reproduction and dies).
In practice, there is no reliable way to prevent crashes in Xenia specifically. The best strategy is to grow multiple small colonies in different parts of the tank. If one crashes, others in different microenvironments may survive. Keeping fragments in a separate system (a refugium or frag tank) provides insurance against total loss.
Common Myths
"Soft corals are just for beginners." Soft corals are beginner-friendly, but they are not limited to beginner tanks. Many experienced reef keepers maintain dedicated soft coral displays or include soft corals in mixed reefs for their unique movement, texture, and coloration. Rare Zoanthid morphs command higher prices than many SPS colonies.
"Soft corals will poison your stony corals." Allelopathy is real but manageable. Activated carbon, protein skimming, and regular water changes keep allelopathic compound concentrations at levels most stony corals tolerate. Thousands of mixed reef tanks successfully combine soft and stony corals.
"Soft corals do not need any care." They are forgiving, not indestructible. Stable water quality, appropriate lighting, adequate flow, and occasional feeding all contribute to healthy, thriving soft corals. Neglected tanks eventually produce declining soft corals just like any other organism.
"You do not need a protein skimmer for soft corals." While soft corals survive without a skimmer, running one removes dissolved organics, allelopathic compounds, and excess nutrients that can otherwise accumulate. A skimmer is less critical for a soft-coral-only tank than for an SPS system, but it still improves water quality and long-term stability.
FAQ
What is the easiest soft coral to start with?
Green Star Polyps and mushroom corals (Discosoma) are the hardiest options. Both tolerate very low light, a wide range of flow, and elevated nutrients. They grow visibly and provide quick feedback that your tank is supporting coral life.
Can I keep soft corals under basic LED lighting?
Yes. Most soft corals thrive under entry-level reef LED fixtures. You do not need the high-end lights required for SPS. Any fixture that produces 50 to 150 PAR at coral placement depth is sufficient. Even some higher-end freshwater plant lights can sustain soft corals, though a reef-specific fixture is preferable.
How fast do soft corals grow?
Growth rates vary by species. GSP and Xenia can double their coverage area in 2 to 3 months. Kenya Trees produce new branches monthly. Toadstools grow steadily and can reach 15 to 20 cm within a year. Mushrooms split every 1 to 3 months. Zoanthid mats expand by adding new polyps at the margins, typically 1 to 3 new polyps per week per colony under good conditions.
Are Palythoa and Zoanthids dangerous to handle?
Palythoa and some Zoanthid species contain palytoxin, which is hazardous if it contacts open wounds, eyes, or mucous membranes, or is inhaled as aerosol. Always wear gloves when handling or fragging. Never boil, microwave, or heat rock with these corals attached. Work in ventilated areas. The risk is manageable with basic precautions but real enough to take seriously.
Should I add soft corals before LPS in a new tank?
Yes. Soft corals are the safest first corals because they tolerate the parameter variability common in newer tanks. Start with soft corals at 2 to 3 months after cycling, add LPS at 4 to 6 months once parameters stabilize, and consider SPS after 6 to 12 months of demonstrated stability. This is the standard progression for beginner coral selection.
How do I stop Xenia or GSP from spreading everywhere?
Place them on isolated rock islands that do not touch the main rockwork. Frag or remove any growth that bridges the gap. For GSP on the back glass, scrape the margins regularly with a razor blade to contain its footprint. Prevention through isolation is far easier than removal after the coral has colonized connected surfaces.