Coral Fragmentation: Not Just For Beginners!

The industry of coral propagation seems to be reaching a state of enlightenment where the knowledge of fundamental procedures for the simple division of reef invertebrates is becoming time tested and even commonplace. It is wonderful to see so many corals in captivity that once were thought to be impossible to keep alive not so long ago now routinely pruned like shrubbery. In gross terms, the captive propagation of coral may be categorized by the action of the event: induced passively, naturally occurring or imposed. Passive induction would include strategies of division that neither result in the immediate production of a free-living clone, nor will they necessarily occur unassisted. Rather, such techniques are methods for spurring budding through fission. Some examples of induced passive division include slicing or notching the periphery of the stolon mat of hardy soft corals such as Star Polyp (Pachyclavularia) or nicking the exposed and illuminated stalk of a leaning (or forcibly tilted) stalk of an Alcyoniid, which often spurs the budding growth of beautiful multi-stalked colonies. Natural strategies of captive coral propagation occur with various manipulations and/or imitations of natural dynamics of the reef environment and are being seen with increasing regularity. They are indeed some of the most interesting events to behold and the subject of another discussion altogether. Indeed, harnessed natural reproductive events like planulae harvest are the future of our trade.

For more than a few years, however, the most common coral propagation technique has been the imposed fragmentation of soft and stony reef corals through cutting, breaking or sawing. By definition, these are deliberate actions taken to asexually propagate a coral and produce divisions that are free-living clones of the parent/donor. They are the fastest and most popular way to farm corals to date, and they are the foundation of our cottage industry. Indeed, imposed fragmentary techniques will likely dominate coral farming until larval rearing techniques are refined.

When setting to the task of cutting a soft reef invertebrate or sawing a stony coral, one must first determine the viability of the specimen and the optimal divisive technique. While many reef invertebrates will tolerate fragmentation so favorably as to not only yield clones, but also express increased growth from such pruning, other corals may suffer measurably instead. It can happen to the extent that the parent colonies are not only inhibited from lending future fragments, but also run the risk of succumbing wholly to infection. One of the first distinctions to be made on a viable candidate for fragmentation is the extent to which the animal might be considered to be mucus producing. Most heavily mucous species are categorically worse subjects for techniques of imposed fragmentation, and are usually more safely farmed with slower constrictive techniques (in octocorals) or passive induced strategies (with scleractinians... especially larger polyped species) with the glaring exception of Acropora, which are quite tolerant of fragmentation. A familiar example of this distinction to aquarists can be drawn in the comparison of leathery Alcyoniids (most Lobophytum, Sarcophyton and Sinularia) to heavily mucous Alcyoniids like Cladiella, Klyxum (Colt), and other "colored" leathers in this family. By "colored" leathers, I mean to convey a categorical generalization that many of the bright yellow and green "finger" and "mushroom/toadstool" corals are often more sensitive to handling (shipping, damage, propagation techniques, etc.) and may fairly be treated with the same consideration we give to so-called mucous corals. On the contrary, a common Sarcophyton is quite close to "indestructible" with regard for propagation techniques. One of my favorite non-traditional farming procedures for the maximum production of divisions with a parent Sarcophyton that one really doesn't want to maul aesthetically is the "Doughnut" technique. The targeted Sarcophyton will have its polyps "waved down," and is then removed to a prepared cutting board for a brief procedure out of water. The specimen is then inverted upon its "crown" while a 1/2" to 1" doughnut of tissue is cut away from the entire periphery of the "crown" (capitulum). After an appropriate run through heated water baths (temperature adjusted to match system water) to purge any mucus, the parent is to be returned to the display in exactly the same position from which it was taken. Strong and appropriate water flow on the healing parent will help to prevent infection and form a callus on the incised wound on the "crown," perhaps in mere days. In as little as two weeks, the assault may hardly be evident at all on the parent. The incised doughnut of tissue can be chopped into equal sized pieces, tossed into a rubble trough for growout, or be stitched/glued individually. The creative sort might even let the ring settle and grow out wholly undisturbed in a most unique shape! By comparison with a mucous animal, nearly all such maneuvers described above would not be readily possible like with a common branching Colt coral (Klyxum), for example. Such a coral will barely tolerate the simple cutting of branches, which are then notoriously difficult and slow to settle and attach to a new hard substrate. Tip: don't waste your time on super glue or natural settlement here... use a single quick stitch (use gloved hands or tweezers to reduce mucus stimulation) through the base of the stalk of the division and tie it off to a hard substrate. After several weeks, or when the animal is apparently secure, snip and extract the discreet nylon stitch. For propagating such mucous species, slower constrictive processes like the use of plastic cable ties initiate very little or no mucus production and are an arguably better method of propagation here than cutting. The division often attaches conveniently to the "handle" of the constrictive tie within days or weeks of the process before separation from the parent. It is a safer, albeit slower, process. And while some mucous coral like the Klyxum described above may be successfully cut, they suffer comparatively higher rates of infection and poorer survival when compared to leathery Alcyoniids like common brown Toadstool/Mushroom leathers (Sarcophyton species). The reason for mucous species suffering readily is quite straightforward and apparent. The sudden insult of handling and fragmentation stimulates the animal's strong mucus producing response; mucus quickly stimulates the growth of normally colonizing bacteria, and the presence of an increased population of bacteria consuming the mucus increases the chance of some of the opportunistic little devils gaining a foothold into the recently insulted tissue. In addition to the mucous corals, many Neptheidae may also benefit from similar considerations, as they will often act stressed as if sapped when cut with many never to return to their full glory, or even to survive repetitive incisions. It is just as well, from the coral farmer's point of view, to not impose cuts on Neptheids, as many will naturally yield more divisions of coral in the long run by branchlet dropping. Even better still, many Neptheid colonies, when left undisturbed to mature, will reproduce via planulae (asexually brood-spawned clones in pouches have been observed in captivity). Perhaps from these brief examples, one can see that there are more than a few considerations when propagating a soft coral, depending on an aquarist's long-term goal for the animal and their willingness to take chances with its survivability.

The candidacy of scleractinian corals for imposed fragmentary techniques needs to similarly consider mucous responses, but more importantly to address morphology. Some stony corals are ridiculously easy to fragment, like phaceloid Euphylliids (branching "Hammer, Octopus and Torch" types for example). By separating branches in the most obvious fashion, one is likely to increase available light and water flow in a favorable manner for each large polyp, and there is no propagating "technique" to speak of. The same generally holds true for most digitate and so-called "SPS" corals. With more massive or encrusting colonial formations, however, successful fragmentation paths are less conspicuous... at least at first. Take, for example, the common "Closed Brain" corals: Faviids and Mussids, by and large. Comparing two popularly represented genera in the trade of these corals, Favia and Favites, one is faced with a great contrast in candidates for imposed fragmentation! The corallites on Favia species (plocoid forms) are distinct and separate while cerioid Favites corallites have shared walls. Colonies of Favia are subsequently fragmented more easily with the path of a saw blade carefully run between the walls of pronounced polyps. Some species of Favia are especially forgiving as corallites are raised and well spaced, which helps to insure that little or no damage is imposed overall. There is a comparatively lower risk of collateral damage to individual polyps in a fragmented colony of a sawn Favia than Favites. The difficulty with Favites, on the contrary, is that significant damage will inevitably be imposed upon the shared polyp walls with the path of a saw blade. Favites may still be sawn, but certainly at a greater risk to the parent and divisions. Please refer to the illustrations and photo below for a pictorial comparison.

Other forgiving scleractinians include Blastomussa merleti and Galaxea species, both of which have tubular corallites joined by calcareous "plates" that are easily separated with a letter opener or saw blade (stationary or power saw). Although they may appear to be rather integrated in form, they are most assuredly "individual" in nature, and quite able to live separated from each other. Fast growth for fragmented divisions often follows upon liberation. There is no love lost between divided polyps of such colonies that apparently fare as well or better on seperation with some breathing room (again, probably due to stimulation from improved light and water flow). Please observe the simplified diagram and comparative photograph below illustrating the forgiving morphology of such scleractinians with conspicuously tubular corallites.

When sawing scleractinian product, fine toothed, high-speed, masonry blades work best but other less expensive saw blades might also work well, particularly for less dense scleractinian skeletons. Please be sure to always obey safety rules for operating power tools. Scleractinian skeletons can and do splinter, and protective eyewear is especially critical. A hand-held rotary tool with a steel cutting wheel is quite versatile and useful for small and porous skeletons (Tip: avoid using the stone composite blades as they shatter too easily when sawing carbonate material). Large corals and very dense skeletons might require the use of a table, wire or band saw. Even the abrasive blades of tile and glass saws have been used with great success on living stony coral.

Once the gross identification of key characteristics of viable propagation candidates has been addressed, the actual business of fragmenting a coral is rather straightforward. Octocorals and other soft reef invertebrates (like zoanthids and corallimorphs) are generally cut by razor, scalpel, knife or scissors. Digitate scleractinians with light to moderately dense corallums ("skeletons") can be fragmented by leverage with pliers, scissors, poultry shears, letter openers and the like. Fragmentation with leverage by hand is generally not recommended because of the unnecessary collateral damage to corallites under the crushing grip of fingers. Such technique also lends itself to unpredictable break lines and portions. And most importantly, it puts the aquarist at risk for a nasty infection through a new or previous break in the skin (Vibrio, Mycobacterium, even sudden and contagious urges to listen to bad lounge music!). Fragmentation of scleractinians by sawing is necessary for more dense skeletons. Forgiving corallums include some plocoid, phaceloid, flabello-meandroid, massive and encrusting colonies. Scleractinians with thick columns and laminae may also favor a saw rather than an aggressive break. Viable candidates, just to mention a few specifically by genera include: Favia, Galaxea, Hydnophora, Blastomussa, Turbinaria (an excellent choice), Fungia (saw pie-shaped wedges) and Pavona. And, it is well known that most of the Pocilloporids (Seriatopora, Stylophora and Pocillopora) and Acroporids are quite forgiving to asexual fragmentation. Some of the best bets for fragmentable soft coral include, but are not restricted to: Lobophytum, Sarcophyton, and Sinularia species. It really isn't practical to name all of the "hardy" soft coral and reef invertebrates for coral propagation. There are tens if not hundreds of great choices. The few listed here are a simple offering especially to the newest coral farmers. With the kindness of most every reef aquarist in our fold, any curious mind can gather additional recommendations from fellowship in a local aquarium society or on the Internet.

When approaching the propagation of a coral, try to select the largest possible division. Fast clean cuts with a razor or scalpel are preferable to the crushing action of a scissors. Very sharp scissors, however, are generally useful and perhaps easier to employ for most aquarists. When using a single edge blade like a scalpel, the action of the knife should be a continuous stroke. Serrated or repetitive cuts increase the likelihood for infection and prolong the healing and attachment process, much like a cut from a razor blade will heal better and faster than a dog bite. On branching soft corals, cuts should be made at the valley of a fork in a branch for aesthetics, if no other reason. On flatter or less thinly branched octocorals, convoluted lobes (like some forms of Lobophytum, Sinularia and Sarcophyton) should be severed from the "peaks" rather than the "valleys" of the "crown" (capitulum) to reduce the chance of infection indirectly from settling detritus. Noted author, aquarist and karaoke singer, Eric Borneman, had brought to my attention a very illuminating suggestion with which I strongly concur about the nature of coral infections commonly ascribed to the very matter, detritus, itself. It is now theorized that such necrotic areas suffer tissue death by detritus from local anoxia, "which may very well be bacterially mediated" (Borneman, pers. comm.). The premise is that suffocation or stifling of the microlayer of diffusive water that surrounds a coral directly causes tissue death from anoxia and increased biotic activity (bacteria consuming precious little oxygen). This phenomenon may be the causative factor in events of coral disease on reefs following storms which drop suffocating sediments on corals poorly evolved to shed them. When Eric suggested this to me it rang a clear bell and reminded me of the like infections on coral seen in shipping bags that cannot be ascribed to detritus in poorly circulated aquaria or sediments on storm ravaged reefs. Yet, the extended transit of coral in a shipping container imposes a like level of suffrage in stagnant water. In all three scenarios there is a common thread of local anoxia followed by symptomatically similar infections. Indeed, aquarists should take this suggestion to heart with due consideration of truly adequate water flow in aquarium husbandry particularly when faced with so-called "mysterious" necrotic infections of coral.

All propagation is best conducted in a dedicated basin or remote aquarium to isolate the noxious compounds produced by corals under duress. Temperature stable (heated) water baths and holding tanks are necessary for extended periods of work. Let me be clear, too, what I mean by "heated" water baths. I have been kindly reminded by my friends and the science editors of this format, Borneman and Shimek, that from the fields of scientific discipline, a "heated water bath" is an inhospitably hot environment in laboratory applications. From an aquaristic point of view, however, I mean only to suggest that the bowls or other prop vessels should not remain unheated if procedures will take more than a few minutes. A sharp temperature drop can be very stressful for marine life as many folks are sadly aware from experiences with receiving shipped animals. So, for the purpose of this article, let me proffer that any reference of mine to a heated water bath refers to a larger vessel in which the prop buckets or bowls are immersed; the water in said vessel is to be heated with a thermostatic aquarium heater to maintain a temperature similar to the system from which the coral was taken. The propagated parent is to be returned to the aquarium system in the exact same place and position that nurtured it prior to the farming technique. A run through a series of holding baths for the purging of mucus and noxious compounds prior to reintroduction is recommended with propagated coral. A small amount of iodine may be added to the bath water with the hope of antiseptic benefits (one drop of undiluted Lugol's iodine per five gallons of heavily aerated water will provide a solution for short baths of ten to fifteen minutes for coral). All bath water is to be discarded. The fragmented divisions may then be placed into a rubble trough for natural settlement and growout, or secured individually.

Ultimately, there is no single, ideal technique or size of division for severing tolerant soft corals and reef invertebrates. For producing a second, full-sized clone of a soft coral in the shortest possible time, a longitudinal or transverse cut may be employed. Basically, a "Leather" coral, for example, can be cut exactly in half lengthwise to produce "mirrored" divisions, or transversely by removing the capitulum with a small portion of the stalk. In the case of the latter, the headless trunk will heal and begin to form new polyps and a full capitulum within weeks. The severed capitulum will attach even sooner with a proper securing technique. Such decisive action produces two full sized colonies within months; it is a process that would otherwise take small fragments the better part of a year or more to realize. The harvest of smaller fragments is generally safer for donors, however. The longitudinal or transverse split of a coral is somewhat more of a risk. After any act of fragmentation, success may be assured if the participants show no signs of deteriorating tissue (necrosis) within several days to a week. Indeed, pathogenic conditions are expressed and develop quickly in such cases rendering infected tissue effectively into "mulch" in a matter of hours (that is to say, a rotting pile of tissue... which is more like compost, than mulch, on further consideration <G>). As an illuminating bit of humor for the new coral farmer who is concerned for the piqued, polyp-less state of a freshly propagated coral, I offer the following wisdom: if you are not sure if the fragment or parent is dead or not... it is not dead! Within hours, a dead octocoral transforms into a dissolving, foul-smelling slurry. Let there be no doubt that such an animal is dead, and be sure to remove any dying coral promptly! It should go without saying that the handling of any living coral tissue in aquariology should be kept to a bare minimum, and conducted with a gloved hand as often as possible.

The imposed technique of severing coral fragments gives a coral farmer ultimate control over portion sizes and shapes among farming techniques, and liberates one from the constraints of time with passive and natural strategies. More than any other technique of coral propagation, severing relies on the good judgment by aquarists that the aquarium system is running in an optimum condition and that the health of the coral is superb. Otherwise, the assault of an imposed technique on coral can invite devastating infections that not only threaten the lives of the parent and division, but the health of other animals in the system with other complications. When successful, severing techniques encourage new growth or fissionary budding along cut edges of the parent as well as relatively fast settlement of fragmented divisions. The cut edges of soft corals may be placed nearly or directly facing downward for natural attachment. The cut edges and exposed corallum of scleractinia, however, are almost never to be set squarely facing downward (with the exception of a complete encasement of the exposed break by epoxy or cement). Forcibly stifled scleractinian tissue is rather susceptible to infection and fares better oriented in a position with optimum light and current showering the exposed break. From an aesthetic point of view, it is a small matter, as the fragment needs to adjust to exploit available light and water flow from most any position and will look quite natural with new growth in time.

It seems appropriate then when contemplating the action of taking a scissors or saw to a living animal that some preparation and familiarity is called for with necessary dynamics for conducting the work. Some of the fundamental components of a coral-farming project include:

Bright, adjustable lighting: overhead, directional and variable lamp fixtures (Disco ball optional...heehee)
Wet tables (areas where water can be spilled and cleanly channeled to drains)
Dry tables
Holding tank(s) with system water for colonies waiting processing (fragmentation or securing)
Heated water bath for extended work time with parents and divisions
Safe and ready access to drainage and electricity (with GFI outlets)
Comfortable working space, chairs, tables
Clean-up and sanitizing supplies
Clean, dry, absorbent towels
Waste removal
Ventilation
Running water/sink

Protective eyewear
Latex gloves
*Samurai sword for corals that fight back in propagation (optional)
A contingency plan should reflect awareness of emergency power shut-offs, poison control phone numbers, contact information of knowledgeable aquarists if assistance is necessary, etc.

* Please do not underestimate the need for a first aid kit unless you are fully prepared to submit to Darwin's evolutionary theory in motion for a species to eliminate its own genetically inferior representatives (Hmmmm...? Cheeky advice from an author dull enough to poison himself three times with palytoxin, don't you think?) Coral propagation may involve scalpels, razor blades, electric saws and poisonous animals. Please exercise due caution and preparedness. Also keep a fire extinguisher nearby; it is not really necessary but lends an air of danger to the operation. It also makes your job look very important to onlookers.

Plastic cable ties (AKA electrical zip ties)
Cyanoacrylate/super glue, hot glue, underwater epoxy
Dental cement, fast-drying cement (hydraulic cement)
Scleractinian rubble (crushed live rock, aragonite, coarse calcite gravel/shell)
Floral picks, toothpicks (plastic), rubber bands
PVC couplings/collars (for containment while diffusing water flow)
Various diameters of rigid plastic tubing (1/8 inch to 2 inches)
Portland cement, aragonite sand, etc. (for making plugs, disks)
Seashells (sterilized...boiled or bleached - free of organics)
Needle and nylon thread (a quick stitch through most soft coral is the fastest/most assured method)
Plastic mesh (rain gutter guard, bridal veil, fruit netting, and the like)
Shallow plastic cups or dishes

To summarize... do consider some basic rules for producing divisions of coral through fragmentation:

It seems like obvious advice, and indeed it is. Surprisingly, many aquarists conveniently or ignorantly (as in, without other knowledge) forget this cardinal rule of coral propagation. While it is true that many corals can reproduce under stress, and even as a final act before death, maximum survivability with asexually fragmented divisions is achieved with prime parent stock. The propagation of unhealthy or unstable animals not only increases the risk of mortality among divisions, but also dramatically increases the risk of infection and mortality among parent stock. It can even lead to the proliferation of a contagious pathogen, which puts the lives of other captives in the system at risk. The best results in coral propagation are achieved when only healthy corals are propagated. Most donors should be maintained undisturbed in the system where farming will occur for a minimum of six months prior to the event and demonstrate normal (and hopefully outstanding) polyp extension and behaviors.

Although I personally prefer sharp poultry shears for many coral propagation techniques, I must admit that sharp razors or scalpels are preferable to scissors. When used to sever coral tissue, scissors must crush, pinch or squeeze some tissue in the process of cutting. This can cause damage to sensitive corals and extend the healing process. A clean fast cut with a razor-like edge is generally preferable in coral propagation.

Fragmented Donors and Divisions of Coral Should not be Moved Post-Operatively...

The donors and products of asexual fragmentation should be maintained in their original aquarium systems after assisted propagation techniques. Movement of "wounded" corals from their established system dramatically increases mortality and risks of infection. The stress of acclimation to new water quality in addition to the trauma of propagation can cause great harm to parent stock and divisions.

... in holding tanks and heated baths. The production of mucus and noxious compounds in defense of the assault of propagation, as well as the influence of competitive species, can create a harmful or poisonous environment. At the very least, there is an increased chance of pathogenic and possibly contagious infection with the production of excessive mucus in crowded environments.

... for corals held pending, during and following propagation techniques. The production of mucus and noxious compounds is inevitable with most species of coral using farming techniques. It is important for the health of parent stock, divisions, and other captives in aquarium systems, that such deleterious elements be contained and discarded before participants in propagation are returned to original housing. Heated baths (thermostatically adjusted to maintain water temperature similar to the system from which the animal was taken from) reduce stress and the production of harmful elements during farming procedures. Sequential baths or dips insure the effective purging of undesirable elements like those described above. Five to fifteen minutes with vigorous aeration or circulation in holding vessels should be sufficient to purge mucus. **A water bath can be made simply with a shallow vessel (aquarium, plastic trough) or even a plugged sink. In the filled bath, a thermostatically controlled heater maintains adequate water temperature for livestock holding bowls and vessels immersed and extending just above bath water. This is critical to prevent stress from the temperature drop in small volumes of water used to hold livestock during propagation

Although all asexually harvested fragments are clones with ultimately the same potential to produce like individuals, the practical application of various propagation techniques can improve success with growth and survivability. Larger segments are logically stronger and more likely to demonstrate greater durability and survivability. More specifically, however, segments should be a minimum of one inch in length and are most successful when fragments are greater than three inches in length or diameter. Segments of branching species are more viable with one or more forks. Soft coral divisions will establish and grow faster if taken with polyps from a branch or part of the "crown" (capitulum), rather than a section of the stalk and without polyps. As always, avoid excessive handling of living tissue using gloved hands whenever possible.

Some coral produce little or no mucus under stress and from handling, while others produce extraordinary amounts with the slightest provocation. Mucus production may cease within hours, or continue for days. It is critical to remove such organic product, or risk the proliferation of undesirable microorganisms upon vulnerable cut or damaged areas on corals. The chance and portal of infection is obvious, and can be controlled or reduced with appropriate water flow. Bursts of current will often serve mucous animals well when they are under stress.

... through regular partial water exchanges, efficient protein skimming and small, frequent applications of quality chemical filtration media (carbon, PolyFilters(tm) and the like).

... are at least indirectly stimulating to stressed coral, and conducive to overall, high water quality. The use of ozone, protein skimmers, iodine supplements and ion exchange resins are some of the most common ways to improve water quality and decrease the level of dissolved organics (beyond good old-fashioned water exchanges). Such water quality, likewise, is not usually conducive to competitive growths of nuisance organisms, like encroaching algae species.

... and consistently conduct proper, regular water changes, especially when nutritive elements necessary for growth are not clearly defined. Consistency in aquarium husbandry can be a significant boon to mariculture efforts, and can make the difference in otherwise comparatively similar systems.

In closing, at the risk of sounding like I am trying in part to cultivate a mystery around coral propagation, I believe that if there were one word to summarize successful mariculture, it would be finesse. Applied science and discipline logically explain the bulk of progress earned. Intelligent guesswork and good fortune also account for more discoveries than most of us would care to admit. But in all events, the subtle and nearly inexplicable ability for conducting coral propagation with finesse is the crux of it all. Let me be clear about this: I do not mean to imply that some people are "gifted" to grow coral when others are not. Quite the contrary, I believe that intuition for successful aquariology is the product of considerate and extensive study of subjects, and can be achieved by anyone with the desire and resolve. There is no mystery at all, in fact. In gross terms, intuition and finesse are most likely the products of observations and lessons learned well from experience. And, please consider that experience alone does not make one wise. Just because somebody has been doing something a certain way for years does not make him or her correct, but instead that they just might be inflexible. Learning from experience is hard work, indeed, and humbling sometimes if you are doing it correctly.

It is important to remember that activities conducted to improve the survivability of propagated corals address both the parent/donor and the fragmented division. Assumedly, a coral farmer is interested in long-term gains or at least in preserving the genetic representation of a given animal in the collection. For this reason, it is especially important to focus on the needs of the parent stock, particularly after imposed procedures.

Finesse in reef aquariology is an acquired skill that guides an aquarist to make subtle and almost intuitive decisions about water quality and maintenance, troubleshooting, diagnosing ailments and propagation techniques. It is a matter of knowing how much is enough, and when is too much. As with any education, an aquarist learning the new field of coral propagation must be open-minded, but not careless... experimental, but judicious.