When I ask friends to describe their ideal coral aquarium, there are two major themes that come up. Many people want to have a large tank filled with Acropora (Acros), Montipora Plate corals and other Small Polyp Stony (SPS) Corals. Others hope for a mixed reef tank, buzzing with color and energy as fish and invertebrates fill every level with the colors and textures of a coral reef.
The challenge is that it takes a lot of money to fill a large tank with corals purchased online or at your local fish store—and every time you make a purchase, you have no idea whether that coral is going to survive in your tank. If you are like me, you probably hate wasting all that money on a large piece of coral, only to watch it shrivel away and die in your tank. Wild-collected corals travel long distances in some challenging living conditions before they make it to your home aquarium, and many of those specimens are damaged and dying before you get them home.
Image by Tappinen
In the next three blog posts, I will show you how some successful reef aquarium hobbyists are able to fill their tanks with corals that are already proven to grow well in their tanks. These aquarists are also able to trade with other hobbyists to acquire some of the corals that grow best for them, and many are even able to use these secrets to make a little money on the side.
Ok, they aren’t really secrets, but what I am talking about is fragging corals.
Hi, I’m Albert Ulrich the author of The New Saltwater Aquarium Guide, which has been a #1 Bestseller in the Aquarium and Fish category in the United States, United Kingdom, Canada and Australia on Amazon. I have been published in Aquarium Fish International and Aquariums USA magazines and I have been blogging online about the hobby here since 2009.
I’m passionate about all things fishy, but my favorite part of the hobby is helping people learn from the mistakes I have made. One of my biggest regrets in this hobby is that I waited too long to try fragging corals. I was scared I would kill the corals I was trying to frag, worried about the expense, and hesitant to take any of the corals out of the water and expose them to the air, let alone slice them up. My first attempt was with a mushroom coral, and I can still remember how nervous I was—my hands (almost) shaking as I carefully placed the rock in a bowl of water, afraid the air would damage the coral. I watched the oozy, curly filaments of the innards and wondered, “What have I done?” That desperate feeling got even worse when I put the open bowl back into the tank and watched the shreds of Mushroom Coral drift away to some invisible spot behind the rockwork, too difficult to dig out. Suffice it to say that I have had a lot more success since those early days, which is why I am here, shouting from the rooftops, “It’s OK. Come on out and frag your corals!”
One of my favorite aquarium hobby books is the Book of Coral Propagation by Anthony Calfo. I didn’t have the confidence to frag corals before that.
If you have coral in your aquarium, but have not tried fragging yet, you may be blown away once you start. Fragging opens up new possibilities for growing your collection, sharing with others, and learning more about coral biology. However, it’s important to be aware of some common pitfalls that beginners often encounter:
- Infection and Disease: Using unsterilized tools or working in unsanitary conditions can introduce bacteria or pathogens, leading to tissue loss or death. Prevention: Always sterilize your tools before and after use, and work on a clean surface.
- Tissue Recession or Poor Healing: Fragging unhealthy or stressed corals, or making rough, jagged cuts, can cause slow healing or tissue loss. Prevention: Only frag healthy, well-established corals and use sharp, appropriate tools for clean cuts.
- Frag Detachment: Frags that are not securely attached can be lost to strong currents or buried in sand. Prevention: Use proven attachment methods and check that frags are firmly fixed before returning them to the tank.
- Stress from Handling: Excessive air exposure, rough handling, or prolonged time out of water can stress or damage corals. Prevention: Minimize handling time, keep tissues moist, and return frags to water promptly.
- Delayed Recognition of Problems: Early signs of trouble include tissue recession, discoloration, or failure to attach. Prevention: Monitor frags closely for the first week and be prepared to intervene if issues arise.
By anticipating these risks and taking simple precautions, you can greatly improve your fragging success and coral health.
Fragging isn’t exactly the same thing as ‘breeding’ corals; it is actually genetic cloning, which is a zillion times easier than breeding corals. Corals are amazing creatures that are genetically programmed to recreate identical clones of themselves from just about any surviving piece of tissue. Take a second to appreciate how wickedly cool and amazing that is. Could you imagine growing a duplicate version of yourself from a locket of hair or a discarded fingernail? That’s the kind of stuff comic book heroes and corals are born to do.
You may be wondering if it is safe…or even natural…to hack your corals to bits. What I can say about that is there are scientific studies that have shown that corals have this super power to make clones of themselves through fragging even as embryos. So, in other words, even teeny, tiny coral babies are genetically programmed fragging machines. But I didn’t know that, when I first started out.
Fragging supports responsible aquarium practices by reducing demand for wild-collected corals. By propagating and trading frags among hobbyists, we help preserve wild reefs, promote hardier strains adapted to aquarium life, and foster a culture of sharing and sustainability. Ethical fragging can be a positive force for conservation and the long-term health of the hobby.
So what exactly is coral fragging? In a lot of ways, coral fragging is made up of equal parts reef gardening, coral breeding/proliferation, and mad science project. In the same way that it is important to prune back the branches of a tree or a bush to achieve a desired shape or keep one plant from overgrowing another, cutting back your corals is a great way to achieve a desired look in your tank and make sure your corals don’t fight and try to overtake each other. Fragging is also a way to increase the number of colonies in your aquarium, effectively splitting one colony into many—but the process of fragging often takes on the appearance of a mad science project, as you snap, cut, or slice up the coral colony and then mount the fragments (called frags) onto rocks, shells, or any other reef-safe material you can get your hands on.
Note the white filaments oozing out
If you only take away one thing from this article, take away this—short exposure to the air won’t hurt your corals.
Most corals naturally experience air exposure during low tides in the wild, and are adapted to tolerate brief periods out of water. For most species, a few minutes in air is safe as long as tissues are kept moist. However, delicate species (such as some LPS and certain soft corals) may be more sensitive, and prolonged exposure can cause desiccation or stress. As a rule of thumb, try to keep air exposure under 5 minutes and always return the coral to water promptly if you notice tissue drying.
Four universal stages to fragging corals
One of the things I have discovered, over the years, is that once you have learned a few basic techniques for fragging corals, you have the knowledge to frag most of the commercially popular coral species. For example, there are 4 stages to coral fragging that are common across just about any fragging method:
- Conditioning
- Preparation
- Creating the frag
- Attachment
Conditioning
Healthy corals recover better from fragging than damaged or sick corals do. It is generally a best practice to ensure your coral is healthy and growing in your tank for a few months before you try to frag it. You want to make sure you can meet the coral’s environmental and nutritional needs first before you start fragmenting off pieces.
- Why does health matter? Corals heal by regenerating tissue over the cut or broken area. This process requires energy reserves and is most effective when the coral is not stressed by poor water quality, pests, or recent relocation. Stable parameters (temperature, salinity, alkalinity, calcium, and magnesium), adequate lighting, and good flow all support rapid healing.
- Signs your coral is ready for fragging: Look for strong polyp extension, vibrant coloration, visible new growth (such as new branches or encrusting edges), and no signs of tissue recession or pest infestation. Avoid fragging if the coral has recently been moved, is recovering from disease, or shows signs of stress.
Preparation
Most coral fragging is done on a countertop or table outside of the water—if you are fragging a Soft Coral, or a Large Polyp Stony Coral they are going to look completely different on your counter than they did in your tank, the moment you took it out of the water. You want to make sure you think through your fragging strategy and identify where you plan to make the cuts and set up your gear before you take the corals out of the tank, to minimize trauma to the coral and ensure you are able to make a nice, clean frag without causing unnecessary damage to the coral’s tissue.
- In-Tank Fragging: Minimizes stress and risk of contamination, especially for large or delicate colonies that are difficult to remove. However, access and visibility may be limited, and precision cuts can be harder to achieve.
- Out-of-Tank Fragging: Allows for better access, visibility, and control, making it easier to make clean cuts and attach frags securely. However, it increases handling time and risk of air exposure or contamination if not done carefully.
Choose in-tank fragging for large, established colonies or when removal is impractical. Use out-of-tank fragging for small, easily handled corals or when precision is needed. Always minimize handling time and keep tissues moist.
Creating the frag
Once you have conditioned the coral and gotten prepared, you have to create the frag. This is the part where you actually cut, chip, saw or otherwise break-off a fragment of the coral. There are a few exceptions, where the corals actually make fragments of themselves (branch dropping or pedal laceration, for example), but most of the time, you will have to get your hands dirty and cut, saw or snap the coral. There are 5 basic cutting techniques that can be used to frag the majority of coral species commonly available.
| Coral Type | Common Cutting Techniques | Best Attachment Methods |
|---|---|---|
| Branching SPS (e.g., Acropora, Montipora digitata) | Snapping, Sawing | Superglue to frag plug or rubble |
| Encrusting LPS (e.g., Favia, Montipora capricornis) | Chipping, Sawing | Epoxy or superglue to rock/rubble |
| Soft Corals (e.g., Xenia, Kenya Tree) | Slicing, Pinching | Rubber band, toothpick, or mesh over rubble |
| Mushrooms & Ricordea | Slicing | Plastic container & mesh, rubble in low flow |
| Large Polyp LPS (e.g., Euphyllia, Acanthastrea) | Sawing, Splitting | Superglue gel or epoxy to plug/rubble |
Key factors influencing technique selection include coral skeleton type (hard vs. soft), tissue fragility, polyp size, and growth form. Matching the method to the coral increases survival and healing rates.
Attachment
After you cut the coral and create the fragment, you generally need to attach that fragment to a substrate—a small piece of live rock or a frag plug. If you make a fragment of a Soft Coral but don’t attach it to anything, it will float away in your aquarium, like my mushroom coral slices did at the beginning of this post. Stony coral frags won’t blow away in the current (unless you have some SERIOUS flow in your tank), but your frag will get damaged if it falls to the bottom or gets covered by the sand. There are 6 attachment techniques. If you can master those techniques, you can frag most of the common, commercially available varieties of coral.
The Secrets of Coral Fragging Success
The “secret” to successfully fragging corals is figuring out what techniques work well for which coral species and having the confidence to execute the cutting and attaching. But each and every method for fragging corals is a combination of one, two or a few of these techniques, based on the individual attributes of the coral you are trying to frag.
For example, if you want to create frags of a Mushroom Coral, so that you could have multiple colonies to fill up your aquarium, or even just to have a few frags to trade or sell at the next Frag Swap, you would use either the chipping method or the slicing method to cut or detach the coral frags and the plastic container and mesh method to attach the fragments to a piece of live rock rubble or a frag plug.
This is blog post #1 of 3. Coming up in articles 2 and 3, I will show you the equipment you need to start fragging the corals in your aquarium, dive deeper into each of the 11 fragmenting and attachment methods for fragging that will tell you how to frag the vast majority of commercially available corals, and finally, I will provide step-by-step directions on how to frag the vast majority of commercially popular corals.
To be continued on the next post…
Please leave a comment below and let’s start a discussion
I want to hear from you. What has kept you on the sidelines about fragging corals? What are your biggest questions about coral fragging?
Al:
You are building my belief that I too can do this Fragging Thing. I am looking forward to the next two posts. You are a confidence builder of epic proportions.
Thanx
Bob, thanks for taking the time to comment–and to give such a nice compliment. I appreciate it. Fragging is like one of the many other things in life that can be intimidating at first–and then once you’ve done it you realize it is not so bad.
Keep me posted on how you progress.
Regards,
Al