While many of the readers of this online magazine are surely experienced enough to have performed some basic coral propagation, in this article we will introduce and display a few unusual techniques. Our hope is to inspire less experienced aquarists to take a chance and fragment some of their own corals while also demonstrating some new tools and techniques for the more advanced aquarists.

We do, however, wish to emphasize the importance of using these techniques only on healthy, well-fed, well-established and growing specimens. The all-too-often seen pattern of fellow hobbyists and basement e-tailing operations attempting to make fragments of yet other fragments, or the practice of slicing and dicing freshly imported or acquired, so-called "rare" corals to quickly make a buck, is disturbing to say the least. This practice is not a recipe for success and, if continued, almost undoubtedly will eventually lead to a total loss of the involved specimens. Corals that have suffered their way through the collection, distribution and retail chain of custody, at times having dealt with insufficient lighting, questionable water quality, and/or the physical abuse of being bagged and shipped, are not prime candidates for fragmentation. They have likely used up a significant portion of their energy reserves simply to survive such conditions and expecting recovery from imposed propagation before stabilization is just too much for many of them to survive. We all should remember that we are dealing with live animals, and act appropriately with due respect for the animals under our care.

Two of the three techniques outlined below are for corals with solitary large polyps. Unlike corals with large numbers of colonial polyps, which can recover more easily from significant tissue loss, cavalier approaches to fragmenting solitary polyps can lead to the loss of the entire animal along with any fragments made. But, be assured that healthy, well-established corals can tolerate and recover quite well from these imposed propagation techniques.

Tools of the trade. Photos by Steven Pro.

Making a Turbinaria peltata "Doughnut"

One of the key considerations for aquarists with most coral propagation efforts is that the mother colony remains attractive after the procedure is complete, particularly if the propagated specimen is being kept in a display aquarium. If the propagation being done is for the express purpose of making money, as in a commercial coral propagation facility, and the appearance of the broodstock is of secondary concern, the effectiveness of the procedure and the number of viable fragments made may take precedence over the appearance of the parent colony. But, most of us are hobbyists performing propagation to control growth in our displays, a sort of aquarium version of Bonsai trees, so the specimen's final appearance is a high priority. In one particular instance/our case, the Turbinaria had grown so large that a magnetic cleaning device could no longer pass between it and the glass and it had grown close enough to a neighboring Torch coral (Euphyllia glabrescens) that they had begun to battle, with the less competitive Turbinaria being on the losing end of this fight.

Turbinaria are extremely hardy, durable, and resilient corals. These attributes make them great corals for a first propagation attempt. And, while all that is necessary to successfully propagate a plating Turbinaria is a hard wall to throw it against and smash it into pieces, what we are going to demonstrate will still yield a multitude of fragments while maintaining an attractive and natural-looking parent colony.

If anyone is not familiar with Anthony Calfo's "Book of Coral Propagation," we (and especially our good friend Anthony!) would urge readers to buy and read this book. In it, Anthony describes propagating a common Toadstool Leather, Sarcophyton, by a means he terms the "doughnut" technique. Below is a brief excerpt detailing this procedure:

"For smooth, mushroom-capped Alcyoniids, an aggressive but very prolific technique can be administered. In preparation, a clean cutting board should sit in waiting with a very sharp scalpel or single edged blade ready nearby. The polyps are to be fully retracted on the 'head' (capitulum) of the leather coral. When ready, the aquarist is to remove the animal from the aquarium system and invert the creature on the cutting board. That is to say, place the animal upside down on its 'head.' Then carefully incise (cut away) a full, one-inch/2.5 cm ring of tissue from the outer edge of the facedown-crown of the animal. When complete, a doughnut of tissue will have been cut away from the donor. The accosted parent is to be returned to the aquarium in the exact same place and position that nurtured it to the point just prior to the propagation technique. The severed ring of tissue is then to be chopped into portions, perhaps one-inch square. The fragmented divisions may then be thrown into a rubble trough for natural settlement and growout, or secured individually…"1

In the case of fragmenting a Turbinaria, much of the propagation technique is the same as for the Sarcophyton described above. The polyps are "waved down" before removing the specimen from the water. But, instead of cutting through the spongy tissue of a soft coral with a scalpel, we used a Dremel-style rotary tool and a side cutting bit, also sometimes called a drywall bit or spiral cutting bit, to cut the tissue and underlying skeleton. These bits look somewhat like a normal drill bit except that the spiral groove has a flared edge which allows the spinning bit to dig into material sideways. These were first seen and popularized by the Roto-Zip people and their infomercials. A hole is drilled through the coral, approximately one inch from the side. Then the rotary tool is worked around the coral maintaining a radius such that a one-inch ring is removed all the way around the coral. After the outer one-inch "doughnut" of coral is removed, it is cut further into approximately one inch squares. After cutting, both the parent colony and individual fragments are rinsed in clean saltwater to clear them of tissue and skeletal debris.

Photos by Steven Pro.

We wish to say how particularly impressed we were with the performance of the side cutting bit. It was quite a bit more maneuverable than the more standard disk cutters used with these rotary tools. These have a limited cutting range because the depth of the cut is limited to the diameter of the cutting disk. And even then, many times the base of the rotary tool gets in the way, running into the coral and further limiting the cutting range. But, this is not the case with these side cutting bits. They are quite nimble, actually, and one could see them being used quite a bit in coral propagation efforts. One instance that comes to mind where they would be particularly adept is navigating your way in the valleys between the shared walls of the so-called closed brain corals.

In our case, we decided to attach the fragments to aragocrete (sand and concrete) plugs with super glue rather than leaving them loose. Within a relatively short period of time, the little squares should begin to round off and take on a plate-like appearance. As for the parent colony, within a month it had healed almost completely. Tissue grew over the exposed skeleton in a matter of days, followed soon thereafter by new polyps.

Fragmentation of an Elegance Coral, Catalaphyllia jardinei

Fragmentation is common in stony corals that contain large numbers of colonial polyps (Acropora, Montipora, etc.) and in those with multiple individual polyps such as phaceloid forms of Euphyllia. On the other hand, stony corals that exist as fused or conjoined polyps such as Catalaphyllia, Plerogyra, Fungiids, etc. present several special challenges, and are generally not regarded as good candidates for fragmentation. Many solitary polyped corals generally have heavy, bulky skeletons which are more challenging to cut. There is also the very understandable concern of losing the entire animal if the fragmentation is not tolerated. Of course, this is the case with any propagation effort. But, it would seem that the risk is perceived to be greater among aquarists when dealing with these types of corals. It appears that the comfort level is high when it comes to breaking or cutting the 'little sticks' that we grow, as evidenced by the multitude that are available for trade or sale, but talk to a group of hobbyists about cutting through a large fleshy polyp and they usually become very squeamish. Additionally, fragments of large polyped corals are thought to take longer to grow into "normal looking" marketable colonies, but that is not the case with Elegance corals as one will quickly see.

Several factors motivated the fragmentation of this particular specimen. The coral had grown too large for the space available to it in the aquarium and had begun to cause significant damage to neighboring corals with its stinging nematocysts. Also, because of the recent apparently poor survival rates of freshly imported Catalaphyllia, it is our hope that this demonstration will encourage thoughtful propagation of healthy specimens that have been successfully kept in captivity for some time, while sparing wild collected animals an almost certain death. Last, but certainly not least, healthy specimens of Catalaphyllia were needed by Eric Borneman for his Elegance Coral Project,) which seeks to identify the causes of this coral's currently poor survival rate.

Although the fragmentation procedure that was chosen for this coral is fairly simple, a lot of planning went into the process to maximize both pieces' chances of survival. The following paragraphs outline the steps taken and their rationale.

Before removing the coral from the aquarium, it was gently "waved down" and shaken in order to retract its polyps, to prevent damage to the polyps caused by the weight of its own water-filled tissue when removed from its aqueous environment. Note the ridge on the skeleton where the growth pattern changed. All growth above this ridge occurred during the 16 months when the coral was in the care of Adam Cesnales.

The coral was placed in a flat tub that was deep enough to cover it, but shallow enough to work easily. This allowed the coral to be manipulated and cut with its skeleton out of the water, but with its tissue remaining submerged.

Both authors recalled reading reports on the Internet of an interesting technique for propagating wall-type large polyped stony corals such as this, but it would appear that the original webpage has disappeared in cyberspace. In these reports, the skeleton was divided, but not the living tissue. A wedge was then placed between the parts, and the connecting tissue was allowed to separate on its own. This technique was obviously born out of fear of cutting large amounts of living tissue. We decided that this would serve only to impede water flow to the tissue that inevitably would be damaged in the process, so this plan was rejected. Causing as little tissue damage as possible remained an important goal, so a significant amount of time was invested to choose the best place to cut. A part of the coral was chosen that would be both accessible to the cutting tool and that would render two attractive coral pieces, while at the same time minimizing the disruption of living tissue.

When a location was chosen for the cut, the same type of rotary tool equipped with a side-cutting bit was first plunged through the skeleton near the polyp. The cut was then extended outward, away from the tissue toward the edge of the skeleton. This offered much greater control than trying to initiate the cut from the edge of the skeleton and then moving toward the polyp. Also, this type of cutter (as opposed to a disc) allowed the skeleton to be cut all the way through in a single pass, thereby making a cleaner cut. The skeleton was much more friable than expected and the cutting tool passed through it with minimal resistance.

The cut was then extended toward the polyp. A bulb syringe was used to irrigate the cut, clearing away the grit and making it easier to see. The intent was to cut most of the way through the skeleton and then break the last 1-2cm, thus avoiding contact between living tissue and the cutting tool. While still cutting about 3-4cm from the polyp, however, a white pasty substance began to run from the cut. Since living tissue obviously had been encountered more deeply into the skeleton than expected, the cutter was stopped and the remaining skeleton was broken.

Once the skeleton was separated, a scalpel was used to carefully cut the tissue connecting the two pieces. Mesenterial filaments, as well as other tissue, were clearly visible at the margins of the cut, and the living tissue extended surprisingly deeply into the skeleton. As the reader can imagine, a prized coral with its "guts" hanging out is not a comforting sight!

The new fragments were returned to the original display and placed as closely to their original location as possible to avoid any additional stress from changes in lighting or current. The fouled water that contained the coral during the fragmentation process was discarded. The authors then took a short lunch break and in the amount of time it took us to consume some pizza, chicken wings, and a few beers, both portions of the coral had expanded to nearly normal size. This image was taken about five hours after fragmenting the coral. Cleary, the procedure was tolerated well! Within about two weeks, new tissue had covered the cut edges.

Photos by Steven Pro.

Fragmentation of a Fungia sp.

As mentioned previously, one of the obstacles to fragmenting large polyped stony corals is the resulting unnatural looking fragments and their slow growth rates. Perhaps no group of corals suffers from this more than do the Fungiids. These corals can be propagated with good survival, no matter how oddly the fragments may appear afterward.

As in the other examples, this Fungia sp. (below) was moved into a pan of water that allowed for easy handling of the coral. The coral was then quite simply cut in half using a disc cutting attachment on a rotary tool. Admittedly, this turned out to be a poor choice as the remarkably hard, dense skeleton stubbornly resisted the tool. Future experiments will most certainly use more aggressive tools such as band saws or chisels!

In addition to cutting the coral, the authors deeply scored one fragment across its septa, and deeply scored the other parallel to its septa. This was done in an attempt to stimulate the formation of anthocauli, or daughter satellite sites where a seemingly dead and denuded parent begins to decalcify and issue buds from along the septa of its corallum. This occurrence is well documented in damaged Fungiids. We also hoped to discover which type of damage would more reliably stimulate anthocauli formation.

The set of photos above are courtesy of Anthony Calfo.

As in the previous examples, the fragmented coral was returned to the same spot in the aquarium from which it was taken, and the fouled water from the pan was discarded. Within a couple of weeks, the tissue at the margins of the cuts was well healed, and within a month, new tissue had completely covered the cut edges. Several months later, both pieces are still alive and appear healthy, but have not formed new mouths where the original one existed. In hindsight, the formation of new mouths would probably have been more likely if the cut had been made across the mouth as opposed to parallel to it. Even considering Fungia sp.'s normally slow growth rate, new growth in this coral has been disappointing. This coral's inability to feed is undoubtedly contributing to its slow growth.

In addition, all of the scoring healed well, but no anthocauli were produced. Take note that even after apparent "abuse," the worst thing that happened was that our efforts did not force the coral to produce daughter colonies. These were rather aggressive techniques and yet the coral survived. The key was how well it was cared for leading up to, and after, the propagation occurred. Again, we would not recommend this or any propagation technique on newly acquired animals.

Overall, despite the survival and apparent good health of the Fungia fragments, they probably remain poor fragmentation candidates. Only the very fastest growing specimens have any hope of becoming large enough and normal looking enough in a reasonable amount of time. The best methods for propagating these corals will probably revolve around finding a reliable method to stimulate anthocauli formation.


Throughout these procedures no dips or prophylactic treatments of any kind (iodine, antibiotics, etc.) were used. It is the authors' opinion that healthy, established corals resist infection very well when provided with good water quality and water movement, and that the indiscriminate use of such prophylactic treatments is not warranted.

In our excitement to demonstrate and record these techniques, the authors shamefully forgot to apply gloves and wear eye protection. Gloves provide needed protection against tissue on tissue contact, which could possibly lead to infection. Flying shards of coral fragments encountered while drilling into coral skeleton is another area where the aquarist is advised to wear some sort of eye protection. While we encourage readers to experiment with new techniques, we also hope that they will be considerate of their own health and saftey as well as that of the corals when performing these techniques.

In closing, we hope that we have presented techniques demonstrating that large polyped stony corals can be safely propagated and that "show" colonies can be aggressively fragmented while remaining aesthetically pleasing. Moreover, we hope that our experience will inspire others to thoughtfully experiment with new fragmentation techniques and to share their experience for all of our benefit!


The authors wish to give special thanks to our mutual friend Anthony Calfo for his advice and counsel in attempting these propagation techniques as well as his assistance in editing this article. Also, a special thanks to Erik Carrillo for the Fungia anthocauli pictures.

If you have any questions about this article, please visit my author forum on Reef Central.


1. Calfo, Anthony. 2001. Book of Coral Propagation. www.readingtrees.com Monroeville, PA, page 383.

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Unusual Stony Coral Propagation Techniques by Adam Cesnales and Steven Pro - Reefkeeping.com