Understanding Coral Fragging Basics
Coral fragging is the practice of cutting a small piece from a healthy coral colony so it can grow independently. Corals expand by forming new polyps, and a frag simply continues this growth on its own once it is separated and mounted. The success of this process depends on three main factors: the health of the parent coral, the stability of the aquarium, and the handling techniques used during cutting.
Only well-established and actively growing corals should be fragged. A coral that is still adjusting to a new system or showing signs of stress will struggle to heal after being cut. Attempting to frag unhealthy corals often leads to slow recovery, tissue loss, or complete frag failure.
Minimizing stress during fragging plays a major role in whether the coral recovers. Corals should be handled gently, cut cleanly using sharp tools, and kept out of water only as long as necessary. Quick, clean cuts reduce tissue damage, while efficient mounting helps the frag begin healing sooner. Returning the coral to stable water conditions promptly supports both the parent colony and the new frag through the recovery process.
Choosing the Right Coral for Fragging
Not all corals respond to fragging in the same way. Some species recover quickly and continue growing with little interruption, while others require careful handling and more controlled healing conditions. Understanding how different coral types react to fragging can help prevent loss and improve long-term growth.
Soft corals, such as leather corals and zoanthids, generally tolerate fragging well. They are less rigid in structure, recover quickly, and do not rely on mineral skeletons when forming new tissue. This makes them good candidates for beginners who are learning basic fragging techniques. Mushroom corals are also forgiving, though they may require alternative mounting methods since they do not attach easily to plugs or hard surfaces immediately.
Stony corals are more sensitive overall. Large polyp stony (LPS) corals have fleshy tissue and a hard skeleton, which requires precise cutting and careful handling to avoid tearing or injuring the polyp. Corals in the Euphyllia group, such as hammer and torch corals, need extra attention because their fleshy tissue can be damaged easily during the cutting or mounting process. Small polyp stony (SPS) corals, including popular Acropora species, can be fragged successfully but usually require very stable water conditions and consistent lighting and flow to heal properly. Their smaller polyps and fast calcium-based growth make them more prone to tissue loss if stressed.
Researching each coral species before fragging is important. Growth rates, lighting needs, tissue structure, and recovery patterns vary widely between coral types. It is best to select corals that are already thriving in your system, understand their specific needs, and ensure that your aquarium can support their recovery. Making informed choices about which corals to frag will improve survival rates and support healthier future colonies.
Essential Tools and Materials
Using appropriate tools and materials can significantly reduce stress on coral frags and support better healing. Having the correct equipment prepared in advance helps ensure clean cuts, secure attachment, and a more controlled recovery process.
At minimum, fragging requires reliable cutting tools. Razors, scalpels, sharp scissors, and bone cutters are commonly used for different coral structures. Stony corals typically require bone cutters or coral clippers to cut through their skeleton cleanly, while soft corals and mushrooms can be separated using razors or sharp scissors. Using dull or corroded tools increases the risk of tearing tissue rather than cutting cleanly, which slows recovery and can create areas where disease or infection may develop.
For mounting coral frags, reef-safe adhesives are essential. Cyanoacrylate gel glues work best underwater because they create a thicker bond and allow fragments to set more securely. Liquid glue does not adhere as well in tank conditions. Reef safe epoxy can also be used for larger frags or mounting on rock structures. Products like our Reef Genetics Reef Glue provide a more secure attachment and reduce the likelihood of frags detaching. Frag plugs, ceramic discs, and live rock rubble are all suitable substrates for mounting. Textured or porous surfaces offer better grip because the glue can anchor into crevices rather than sitting on a smooth surface.
Safety and sanitation are also important. Protective gloves and goggles should be used when fragging, especially for species that may release toxins, such as zoanthids and palythoa corals. Sterilizing tools before and between uses helps prevent the spread of pathogens or pests. Simple disinfecting steps can reduce the risk of bacterial infections developing at the cut site and limit cross-contamination between corals.
In some cases, soft coral frags benefit from temporary support while they attach. Elastic bands, fine mesh, or small containers filled with rubble can hold loose tissue in place until it bonds naturally. Mushrooms and other unattached species often require this approach because glue does not adhere well to their tissue.
Preparing a stable workspace also makes the fragging process more efficient. Good lighting helps ensure clean cuts and accurate placement, while having all materials within reach minimizes the amount of time corals spend out of water. Many aquarists also use frag racks or healing areas with controlled flow and lighting, allowing frags to recover without interference from tank mates or strong currents.
Having the correct tools and adhering to proper handling methods helps protect both the parent coral and the new frags. These simple choices contribute directly to healthier healing and more consistent propagation success.
Common Coral Fragging Issues and How to Fix Them
1. Frag Bleaching and Tissue Loss
Frag bleaching occurs when a coral loses color or begins to shed tissue after being cut. This typically results from stress caused by abrupt lighting exposure, unstable water conditions, or damage during the fragging process. Newly cut frags are more sensitive and may not tolerate high-intensity light immediately after being mounted.
To reduce bleaching, frags should be introduced to light gradually. Rather than placing them directly under strong lighting, position them in lower or shaded areas of the tank and move them slowly to brighter areas over one to two weeks. Proper acclimation helps prevent photoinhibition, which occurs when corals receive more light than they can process.
Maintaining consistent water chemistry is equally important. Sudden fluctuations in parameters such as temperature, salinity, alkalinity, calcium, magnesium, or pH can hinder recovery. Ideally, tanks should remain within stable ranges including 75–77°F for temperature and 1.024–1.026 specific gravity for salinity. Monitoring nutrients and performing regular testing after fragging can help identify issues early.
Observing new frags closely is recommended. Reduced polyp extension, color loss, or exposed skeleton can be early signs of stress or bleaching. Addressing these issues quickly through light adjustment and stable conditions supports faster recovery and prevents further tissue loss.
2. Frag Detachment and Poor Attachment
Frags may dislodge from plugs or rocks if improper adhesives are used or if the mounting surface does not provide adequate grip. Liquid glue often forms weak bonds underwater, while smooth plug surfaces may not allow adhesives to anchor well.
Using cyanoacrylate gel glue is best for underwater mounting. Gel provides a thicker bond that holds the frag securely, especially when paired with textured plugs, ceramic discs, or rubble rock. Our Reef Genetics Reef Glue is an example of a suitable adhesive formulated for coral attachment.
Before gluing, gently drying the frag base or the mounting surface can help improve adhesion. After mounting, frags should be placed in a low-flow area to prevent detachment while the adhesive cures. Larger frags may require rock rubble or epoxy for additional support. For delicate tissue corals, placing the frag inside a small cup with rubble and mesh allows it to attach naturally before being moved to the display.
3. Algae Overgrowth on Frags
Algae can rapidly overgrow frag plugs or exposed skeleton, blocking light and restricting tissue recovery. This typically results from excessive nutrients in the water or inadequate flow in the frag’s location.
Maintaining controlled nutrient levels is important. Reducing nitrate and phosphate through routine water changes, stronger filtration, or phosphate removers helps limit algae growth. Improving water flow around the frag rack or mounting area prevents algae from settling on surfaces.
Cleanup crew members such as snails, hermit crabs, and conchs can also help remove algae, but they should not be relied on as the only solution. Regular manual removal, especially around slow-healing cuts, keeps fragments clear while they regenerate.
Monitoring algae growth early allows for timely intervention. If algae begins to coat exposed skeleton, it may also indicate slowed healing due to stress. Ensuring proper lighting, nutrients, and water movement helps frags regain tissue before algae can dominate.
4. Frag Infection and Disease
New frags are vulnerable to bacterial, fungal, or parasitic infections, especially if tools are not sterilized or if frags are placed in unstable water conditions. Common signs of infection include tissue recession, discolored patches, or white areas spreading along the skeleton.
Sterilizing tools between cuts reduces the spread of pathogens. Using disinfectants and avoiding cross-contamination between colonies limit disease transfer. Coral dips containing iodine or other specialized agents, such as Lugol’s solution, can be used immediately after cutting to reduce bacterial and parasitic risks.
Quarantining new frags or placing them on designated frag racks allows reef keepers to observe healing without exposing the main tank to potential problems. If infection appears, fragging away healthy tissue from the affected area can help save the coral.
Stable tank conditions and good handling techniques provide natural resistance against infections, reducing the likelihood of tissue loss or rapid decline during recovery.
5. Slow or No Growth of Frags
If frags are not showing growth over time, it may indicate suboptimal conditions rather than a problem with the frag itself. Growth is influenced by lighting intensity, nutrient availability, stability of key elements, and proper water flow.
Lighting should match the coral’s natural needs. SPS frags require intense lighting and strong, varied flow, while many LPS and soft corals grow best under moderate light and gentler movement. Stability in alkalinity, calcium, and magnesium is essential for skeletal growth, especially for stony corals. These elements should be tested regularly and supplemented as needed.
Frags may also benefit from targeted nutrition. Fine particulate coral foods, amino acids, and zooplankton-based products can encourage tissue growth and color development. Overly “clean” systems may lack nutrients needed for healthy recovery, resulting in stalled growth.
Patience is important during the healing period. Consistent monitoring, stable tank parameters, and appropriate lighting and flow provide the environment needed for frags to establish and grow effectively.
New Frags and Their Care
Proper care after fragging is essential to ensure that both the parent coral and the new frags recover, acclimate, and continue growing. A frag may initially appear healthy when mounted, but the critical phase begins once it is placed back into the aquarium. During this period, stable conditions, careful observation, and correct placement determine whether the fragment adapts successfully or suffers tissue loss and decline.
New frags should be placed in locations that match their lighting and flow requirements but also consider their sensitivity after cutting. Soft corals and mushroom corals typically require moderate light and gentle flow to avoid detachment or tissue irritation. SPS corals, including Acropora and Montipora, benefit from stronger flow and higher light levels, but it is important to introduce them gradually to intense lighting rather than placing them directly into peak conditions. Easing frags into their final placement helps reduce stress caused by sudden changes.
Using sterilized cutting tools such as bone cutters, coral clippers, or razor blades helps minimize the transfer of contaminants. After fragging, new frags should be mounted securely using reef-safe glue or epoxy, ensuring minimal tissue contact with adhesive materials. Mounting should be handled carefully to avoid tearing frag tissue, especially for LPS corals with large, fleshy polyps, such as torches, hammers, and frogspawn. Once mounted, placing frags on a frag rack or in a dedicated frag tank gives hobbyists greater control over their environment.
Maintaining tank parameters within consistent ranges supports the healing process. Temperature, salinity, and nutrient levels should remain stable, and water chemistry must be monitored regularly for shifts in alkalinity, calcium, and magnesium. These are especially important for stony corals, which rely on proper mineral balance for skeletal growth. Newly cut frags can be more sensitive to fluctuations, so monitoring during the first few weeks is recommended.
Inspection during the early recovery period helps detect problems before they progress. Reduced polyp extension, algae creeping onto exposed skeleton, or irregular tissue coloration may indicate stress. Adjusting lighting, increasing flow around the frag area, or improving nutrient balance may correct early issues. Quarantine or separation from aggressive tank mates also helps protect vulnerable new frags.
Providing appropriate conditions, secure mounting, and continued observation ensures that new frags transition from the fragging process to active growth. By creating a stable and controlled environment during this healing phase, aquarists support healthy coral propagation and help newly cut fragments develop into thriving additions to their reef systems.
Advanced Tips for Successful Coral Fragging
Proper Frag Placement and Tank Environment
Where a frag is positioned in the aquarium has a direct impact on its ability to heal and grow. Placing a frag too close to aggressive neighbors may expose it to stinging tentacles, which can cause tissue damage or inhibit growth. It is important to leave adequate space around new frags so they can expand without competition from nearby corals.
Frags should also be positioned based on their natural lighting and flow requirements. SPS corals benefit from areas with stronger, varied flow that helps remove waste and deliver nutrients, while many LPS and soft corals prefer moderate flow that does not directly agitate their tissue. Sudden exposure to intense light can lead to bleaching or photoinhibition, so new frags should be introduced gradually to higher lighting levels.
Maintaining stable environmental conditions is essential during this period. Even minor temperature or salinity fluctuations can stress newly cut corals. Reliable equipment such as appropriately sized heaters, chillers, and automatic top-off systems can prevent rapid shifts, creating a more controlled setting for recovery.
Monitoring and Adjusting Water Parameters
Consistent water chemistry supports frag healing and long-term growth. Regular testing is important after fragging, as recovering corals may be more sensitive to changes that would not affect established colonies. Key parameters include alkalinity, calcium, and magnesium, which support skeletal development in stony corals. Automated dosing systems can help maintain these elements at stable levels, reducing the risk of fluctuations caused by manual dosing.
Nutrient control plays an additional role in frag health. Elevated nitrate and phosphate levels can encourage algae growth, which may irritate tissue or cover exposed skeleton. Conversely, systems that are too nutrient-poor may starve corals of the materials needed for growth. Maintaining balanced nutrient levels and monitoring them consistently helps provide the optimal conditions for recovery.
Using Frag Tanks and Quarantine Systems
Dedicated frag tanks or quarantine systems offer controlled environments where frags can heal without interference from fish or competition from established corals. These systems allow aquarists to adjust lighting, flow, and feeding practices specifically for frag recovery. They also reduce the risk of pests or pathogens being introduced to a main display tank when new frags are acquired.
Frag tanks also provide easier access for targeted treatments, feeding, or observation. The ability to isolate frags during their most sensitive stage can significantly increase survival and growth rates. Once healed and established, frags can be transferred safely to the display tank.
Frag Rack Management
Frag racks provide organized placement and consistent access to light and flow, but they require proper maintenance. Overcrowding can limit access to nutrients or reduce flow around frags, slowing growth. Adequate spacing between frags ensures each coral receives appropriate lighting and water movement.
Cleaning frag racks regularly helps prevent algae buildup, which can encroach on plugs or exposed skeleton. For encrusting corals or those that spread outward, using rubble or specialized tiles allows tissue to grow more naturally compared to small plug surfaces. Monitoring frag positions and adjusting as needed helps maintain optimal conditions for each species during recovery and growth.
Common Mistakes to Avoid in Coral Fragging
Overhandling and Rough Cutting
One of the most common fragging errors is excessive handling of corals during the cutting and mounting process. Corals are easily stressed when removed from the water, and frequent or prolonged manipulation increases the likelihood of tissue injury. Rough handling can tear tissue, expose skeleton unnecessarily, or damage polyps near the cut site.
Using improper or dull tools contributes to this issue. Jagged cuts made with corroded or blunt instruments leave uneven tissue edges that take longer to heal and are more susceptible to infection. Clean, precise cuts minimize visible damage and help the coral begin regeneration more effectively. Selecting the correct tool for the coral type—such as bone cutters for stony corals or sharp razors for soft tissue—prevents tearing and makes the fragging process easier on the coral.
Reducing handling time, preparing tools and plugs ahead of time, and making swift, accurate cuts all help limit stress and protect coral health. The fewer disruptions a coral experiences during fragging, the faster it will recover.
Ignoring Water Quality and Stability
Even well-cut frags will struggle if they are placed in tanks with poor or unstable water quality. Some hobbyists assume fragging is a mechanical process and overlook the biological requirements that must be met afterward. In reality, the healing phase depends heavily on stable parameters. Frequent swings in alkalinity, salinity, temperature, or nutrient levels can weaken new frags or prevent tissue from regenerating over exposed skeleton.
Reef keepers should monitor elements such as alkalinity, calcium, magnesium, nitrate, phosphate, and pH consistently after fragging. Neglecting routine tank maintenance, such as water changes or filter cleaning, may lead to nutrient spikes that encourage algae growth or bacterial issues around healing tissue. Stony corals in particular require consistent mineral levels to form new skeleton.
Rather than attempting to correct problems after signs of stress appear, maintaining stable, balanced water quality from the moment fragging occurs provides corals with the conditions they need to recover properly.
Neglecting Frag Acclimation
A frequent oversight is placing new frags directly into high-intensity lighting or strong flow without a gradual adjustment period. Sudden exposure to extreme conditions can shock corals, leading to bleaching, tissue recession, or slow healing. Even frags taken from the same aquarium require acclimation because they have undergone physiological stress during cutting.
Frag acclimation should involve gradually introducing corals to brighter light or stronger flow over time. This can be done by placing frags lower in the tank initially, shading them temporarily, or adjusting light intensity over several days. Providing an appropriate acclimation period gives frags the opportunity to recover from fragging stress before adapting to their final placement.
Ignoring acclimation often results in avoidable frag losses. Allowing time for gradual adjustment increases survival rate, promotes healthier tissue regeneration, and prepares frags for long-term growth in their intended location.
Conclusion
Coral fragging is a practical and effective way to expand and maintain diverse reef aquariums, but its success depends on more than simply cutting and mounting coral pieces. Each step of the process—from selecting healthy parent colonies to providing appropriate care during healing—directly influences whether frags survive, adapt, and continue growing. Understanding the most common fragging challenges, such as bleaching, detachment, algae overgrowth, infection, and delayed growth, allows hobbyists to address problems early and avoid preventable losses.
Consistent environmental conditions, proper frag handling, and the use of suitable tools are fundamental to healthy propagation. Stable water parameters, secure attachment techniques, careful placement, and gradual acclimation all contribute to reducing stress on new frags. Taking time to observe coral responses after cutting offers valuable insight and provides an opportunity to make adjustments that support recovery and long-term growth.
With practice, patience, and attention to detail, fragging becomes a reliable method for growing new colonies while maintaining the health of the parent coral. Over time, aquarists can develop successful fragging routines that support sustainable reef keeping, help strengthen captive coral populations, and enhance the overall stability and diversity of their aquariums. By taking an informed and measured approach, coral fragging remains both a rewarding skill and an essential part of responsible reef care.
