Propagation of Small-Polyped
As most people are aware, "small-polyped
stony" corals is a rather
imprecise term because the size of the polyps in stony
(hard or solid skeleton forming) corals is a continuum rather
than a discrete division of small versus large. Nevertheless,
the term generally describes many of the fast-growing, branching,
encrusting, whorl-forming and plating corals that are commonly
grown in captive reef systems.
Fortunately, small-polyped stony (SPS) corals are quite forgiving
of the way they are propagated. Given time and good conditions,
the end product of almost any ham-handed attempt at propagation
will eventually regain a natural-looking colony formation
when provided with the proper conditions. Some of the techniques
described here should help you to minimize the damage to and
unnatural look of your mother colony, and to do the same for
the fragments that you take.
Why Do It?
SPS corals can grow
very quickly in a reef tank with strong lighting and water
motion. When colonies touch, they begin to compete for space
and attempt to sting each other. Sometimes the colonies reach
some type of stalemate, with neither colony gaining an advantage
over the other. In some cases, however, extremely aggressive
corals (Hydnophora, in particular) can burn or digest
large patches of adjacent colonies. Some extremely fast-growing
corals simply shade out their neighbors. After a few years,
most successful SPS-dominated tanks need some colony trimming.
It's a great opportunity to take some fragments and trade
with friends. Your buddy's tank can then serve as a reservoir
for your most prized corals, should some disaster befall your
tank. The continued propagation of captive-raised corals may
also reduce the demand for corals collected from the natural
reef and the energy needed for their collection and long-distance
What Should I Cut Up?
The greatest success always comes
from taking fragments from the actively growing portions of
a colony. Other areas can also be fragmented, but the length
of time these take to begin growing again after fragmentation
may be longer. Fragmenting from a dying coral is least likely
to succeed. If a colony has an infection, cutting a fragment
as far away from the affected section as possible, and possibly
moving the fragment to a different tank, might be the best
way to ensure that the entire coral is not lost.
Assemble Your Tools
It is possible to propagate some SPS
corals with nothing but your bare hands. Some species have
branches that are easily broken off with the flick of a finger.
If a suitable hole can be found to tuck the branch into, and
it is kept immobilized and in contact with the substrate,
many times the branch will begin to encrust onto the substrate,
sprout new branches and form a completely new colony over
time. Some species even tolerate being dropped onto the sand,
and can also form new colonies right where they fall. To go
beyond this simplest method of propagation a number of other
tools are useful.
Counter-clockwise starting from top left - commercially
available fragging shears, special cable cutting pliers,
one of my pairs of trusty (rusty) wire cutting pliers,
a high-speed rotary cutoff tool with two sizes of diamond
cutoff blades and a miniature hacksaw blade holder.
Counter-clockwise starting from top center - commercially
available high viscosity cyanoacrylate glue, part of
a plastic egg carton useful for dispensing the glue,
bottle holder made from a small tube and a sheet of
acrylic, and a large bottle of liquid cyanoacrylate
Counter-clockwise starting from top left - coarse wet-dry
sanding pad glued to wood board (used for sanding base
of fragments flat), needle-nosed pliers (useful for
breaking or removing small coral branches from easily
broken branching corals), chisel (for breaking off outer
whorls of whorl forming corals, or for breaking branching
corals by prying), small concrete squares (substrate
for mounting fragments), and latex gloves (used when
mixing commercially available putty-type underwater
epoxies pictured above).
Probably the most important tool for fragmenting SPS corals
is a pair of cutting pliers. I've been using the same two
or three pairs of rusted out wire cutting pliers for many
years now. I'm very lazy when it comes to my tools; I almost
never remember to rinse them off with freshwater and I do
not lubricate them. This is partly because I use them on a
very regular basis. I just leave them hanging about, here
or there, to be grabbed quickly for the next project. I don't
lubricate the tools because I don't want any toxins from synthetic
lubricants polluting my tanks, and I don't want to have to
wash any lubricants off the tools before each use. I've found
that the quality of the cutting pliers doesn't really matter
much; in fact, high quality cutting pliers with precise action
and fine tolerances between their moving parts can be problematic
with the abuse that I subject them to. After each use in saltwater,
rust will form between the moving parts. The pliers may freeze
up and have to be forcibly worked back and forth until they
free up again (a little water helps here). Each time this
occurs, more and more of the steel between the moving surfaces
wears away, making the joint looser and easier to use. After
enough abuse, so much steel will have worn away that the pliers
will never freeze up again, and are then the perfect tool
High grade specialized stainless steel fragging shears with
sharp cutting edges are available now for the hobby. These
shears are more resistant to oxidation than cheaper standard
shears, but if not rinsed carefully after use in saltwater,
over time they will rust, as well. For certain applications
these shears might have some benefit over my rusted-out cutting
pliers but, in most cases when propagating SPS corals, the
branches are not so much cut as they are crushed or snapped
by the tool's action. Therefore, the tool's sharp cutting
edge adds little benefit and, in the case of thicker branched
SPS corals, may actually be more of a problem. Because the
tips of such a tool are tapered, when extreme force is required
to break the branch the tool flexes too much, and makes the
cut more difficult to achieve.
When I give coral propagation demonstrations at my house,
I always warn the newbies never to use any metal objects in
their aquariums, as the toxins can kill invertebrates and
fish. Then I show them my 10-year-old cutting pliers with
large flakes of rust falling off, plunge the tool into my
400-gallon SPS-packed tank and say, "Don't believe everything
you hear." In all seriousness, many people frequently
dose their tank with iron and various trace elements. While
I understand that steel is composed of many elements, including
toxic chromium and nickel, I've never found a few bits of
rust getting into a functioning reef tank to cause any problems
In the first tools photo above is pictured
a special cable cutting pliers. This pliers, while large and
hard to maneuver, can be useful for cutting particularly
thick or solid branching corals. I've often thought it would
be nice to find a similar pair of pliers, or modify another
pair, but with a larger hole so that the cutting force would
be increased when cutting thick branches. With such a modified
pliers, the cutting force would be applied when the pliers'
grips are more fully closed, a position in which the human
hand can naturally apply more force in a controlled fashion.
Being able to cut branches off corals in a controlled fashion
can mean the difference between neatly cleaving off a single
branch, leaving the colony aesthetically pleasing, or ending
up with a dozen fragments and a mangled mother colony. Whenever
possible, it's usually easier to make a more controlled cut
if the colony can be removed from the tank, or at least brought
near the water's surface.
Other tools that can be useful include a high speed rotary
tool with a diamond encrusted cutoff wheel (mine is permanently
rusted to my Dremel tool). These wheels are surprisingly affordable
and amazingly durable. I've been using the same one for many
years, and have sliced directly through some very hard rocks
and corals. While harder to find, larger diameter diamond
encrusted cutoff wheels may also be useful in some cases.
Hack Up Your Coral
Propagation of an SPS coral with long
branches is really quite straightforward. In an attempt to
maintain the colony's aesthetics, look for branches in the
rear of the colony, or in an inconspicuous area near the base.
It is okay to use branches that might be shaded and that are
no longer growing well. Clip the branches off with your cutting
pliers, break them off using your fingers, or pry and snap
them off with a screwdriver or chisel. When removing branches,
try to minimize the damage to the coral's surface, as this
is the living tissue. Try to keep cut branches out of the
sand, or shake off any debris if they do fall onto the sand.
Whorl-forming Montipora species can be tricky to fragment.
Sometimes their large outer whorls can be removed by hand,
or pried free with a small, flat chisel if the base is not
too thick. All too often, though, the outer whorls end up
breaking into a dozen small, and perhaps less valuable, fragments.
If the colony can be removed from the tank, the diamond encrusted
rotary cutoff tools are particularly useful for harvesting
large fragments. If the colony is too big, or encrusted to
large rocks, I've found that a simple hacksaw blade is useful.
This blade can be handheld or wrapped with a piece of duct
tape. If more force, or a large amount of cutting, is required,
a small hacksaw blade holder can sometimes be used (see first
I generally place my fragments in a small plastic bucket
(photo above), gently dropping them in as I move about my
tank pruning. Though other authors warn not to mix multiple
species in a single bucket, I've never seen a problem if the
corals are not kept together for more than a few hours. One
exception to this, however, are SPS corals of the genus Hydnophora.
After just a few minutes in a stagnant bucket, these corals
will start to digest any corals that they contact.
Fragmentation and Mounting Branching SPS Using
Once the coral fragments are out of
the tank, they can be cut up the rest of the way into the
desired shape and size. I've found that for optimal survival
rates, it's best not to try to cut fragments smaller than
about one inch. This is a good time to remove any sections
of dead coral skeleton that might otherwise serve as an attachment
point for undesirable algae.
I like to grind the fragment's base flat with a high-speed
rotary tool with a diamond cutoff wheel (photo above left).
If the fragment is particularly large, it may be advantageous
to find its balance point, and grind the base in such a way
that the coral can nearly balance on a flat surface. Ideally,
live coral tissue on all sections of the fragment should be
in close contact with the attachment substrate. Having the
base perfectly flat is not a requirement for mounting, but
it does make for a stronger attachment initially, and allows
the coral to encrust faster along its base.
A piece of coarse grit wet-dry sandpaper glued to a small
wooden board can also be used to grind the base flat (shown
above). If it's brushed and rinsed clean in a sink after each
use, the same piece of sandpaper can be used for many years.
The sandpaper is glued to the board so that when it dries,
it remains flat. While it might be difficult to sand a thick
Acropora using this technique, most branching Montipora
are quite porous and can be sanded to a flat base very quickly.
If working with a large number of fragments, this may be much
faster than drying your hand repeatedly before picking up
the high-speed rotary cutoff tool.
After grinding the base flat, the exposed skeleton is gently
rinsed clean to remove any proteinaceous slime by gently rubbing
it with your fingers in a bowl of tank water (photo below
The base is then dried with a cloth or paper towel (photo
above right). Sometimes, with porous branching corals such
as Montipora digitata, it may be difficult to completely
dry the base. Leaving the coral out of the water for a few
minutes may help here. Also, keeping the fragment inverted
will help the water in the skeleton to flow away from the
attachment point you are trying to dry.
Quickly apply the cyanoacrylate glue after drying the coral's
base. With some porous skeleton branching corals, water will
begin to reappear on the coral's base within just a few seconds
of being dried. Only a drop of glue is necessary. Excess glue
will not, in most cases, strengthen the bond, and it will
take much longer for the coral to encrust over the glue and
actually bond to the surface of the substrate. In the photo,
note the "fraggers' nail polish," - cured glue from
a previous propagation session.
At this time I keep the fragment inverted with one hand,
and use a cotton swab to apply a tiny dab of cyanoacrylate
glue accelerator to the substrate with the other hand. Only
a fraction of a drop of accelerator is required. As shown
in the second tools photo, I use a special
homemade holder for the cyanoacrylate glue accelerator to
reduce the chance of an accidental spill of this toxic organic
Once the accelerator has been applied to the substrate's
surface, immediately place the fragment onto the substrate
because the accelerator evaporates very quickly. When positioning
the fragment, make sure that no water flows over the surface
of the glue or the contact point on the substrate before the
contact is made. Once the fragment is positioned, water flowing
onto the bond's surface makes no difference. You will have
only a few seconds to orient the fragment once contact is
made. Usually within 10 seconds the bond is strong enough
that you can lift the fragment without the base falling off
while gently lowering it into a bowl of tank water. If something
goes wrong, and the attachment is not strong after a short
period of time, you can re-dry the fragment and the substrate
and try again.
Multiple fragments from the same colony can be mounted to
the same substrate, if desired. Branches that touch often
anastomose (fuse) as they grow. This, combined with the increased
surface area and multi-point attachment to the substrate,
can result in a very structurally durable fragment that can
withstand the average drop kick from the FedEx guy during
shipping. Branches can also be attached flat against a substrate,
which, in some cases, might force the fragment to create more
numerous, smaller branches than a vertical orientation. Mounting
in a horizontal orientation requires additional sanding or
grinding to remove the outer, growing layer of tissue so that
a good bond can be formed between the fragment and the substrate
using cyanoacrylate glue.
After 10 minutes or so, glued-down fragments can be moved
back into a tank to start the grow-out process. If the fragment
was taken from the underside of a colony, care should be taken
to slowly acclimate
it to stronger light. Here I've shown the use of small
squares of concrete that I make myself. Flat fragment attachment
disks also are commercially available, as are disks with small
shaped pegs on the bottom (www.bostonaquafarms.com),
which can fit into the plastic eggcrate material that many
reefkeepers use as shelves in grow-out tanks. Fragments can
also be glued to just about any hard surface. Some hobbyists
use plastic flower stem holders, or small pieces of acrylic,
ceramic tiles or live or base rock, for this purpose.
While I've described the use of cyanoacrylate accelerant
here, there is no need to use the chemical. Its only purpose
is to speed the curing process. When you are done with your
fragmentation work, and all your fragments are back in a tank,
be certain to throw out the water that was used in the propagation
Fragmentation and Mounting of Whorl-Forming SPS
Using Cyanoacrylate Glue
Diamond encrusted cutoff wheels greatly
simplify fragmentation of whorl-forming SPS corals. The desired
shape and size can easily be cut out of the main colony. It's
usually easiest to cut from the rear of the coral when making
I like to bevel the coral's edge, to make its position on
the substrate more naturally "inclined" (photo above).
As with branching corals, the base is washed clean of proteinaceous
slime and any debris, and the base is dried.
The glue is applied quickly before water can recover the
surface (photo above left). I try to get a thin layer of glue
over the majority of the contact surface, if possible. Next,
the accelerator is applied over the substrate's contact surface
(photo above right).
The fragment is positioned and held for 10 seconds or so.
If the fragments were taken from an area of the colony that
was not receiving much light, they should be positioned at
an angle to receive indirect light in the fragment grow-out
tank. This will give them time to adjust to increasing light
Mounting SPS Using Underwater Putty Epoxy
described the methods of use and hazards of underwater
two-part epoxy, which is particularly useful for SPS corals
such as Anacropora or Hydnophora, or any other
SPS coral that does not effectively encrust.
For SPS coral mounting, the epoxy is pressed onto the surface
and shaped around the edges to form a small crater. At this
point it's best to wait several minutes for the epoxy to start
to set up.
The fragment is positioned and the putty epoxy is formed
up around its base (photo above right). Putty epoxy has no
significant adhesive properties, so it's necessary to cover
enough of the coral so that when the epoxy hardens, the coral
is effectively anchored to the substrate. Corals with particularly
smooth branches can be notched near their base to provide
a place for the epoxy to flow into.
When using putty epoxy on SPS corals, it's important to recognize
that all covered coral tissue will die, and also that while
curing, the putty will heat up and kill any tissue very close
to the edge of the epoxy. In some rare instances the dying
tissue can form a front of diseased tissue that will travel
up the fragment, killing the entire fragment. The probability
of this can be minimized by keeping the coral fragments' base
cool by placing them in a bath of tank water that has good
circulation from an airstone or a small powerhead.
Under good conditions, in a few weeks the corals will encrust
down onto the surface of the substrate, or encrust over the
putty epoxy's surface. The concrete substrates and the epoxy
surfaces will quickly become covered in coralline algae, taking
on a more natural appearance.
People often ask, "How long can
the corals be out of water?" Well, it depends. I've found
that most SPS corals are fine for two to three minutes out
of water. Those that tend to slime a lot tend to be okay for
longer periods of time than those that seem to be dry in a
short period of time. If your fragments look like they have
a dry surface, you need to get them back into water ASAP.
Lugol's dips: I've heard some say that a 10-15 minute dip
in 10-15 drops per liter of Lugol's strong iodine solution
can increase the success rate of fragments. When fragmenting
healthy corals, I've found the success rates to be so high
that I see no need for the expense and extra time required
for a Lugol's dip.
To minimize the risk of introducing coral parasites into
my main tank, I carefully quarantine any corals I obtain from
sources other than my own tanks. If, after the quarantine
period, I decide I want to keep a coral long-term in my display
tank, I mount it on a large rock using the methods described
in this article. I often use rocks with holes bored in their
base. Because my tank's rock structure also has holes drilled
in its top surface, this allows me to position the colonies
wherever I like using acrylic rods poked though the holes.
This methodology allows the entire colony to be moved about
the tank if I need to "remodel," and also allows
easy removal of the colony if I need to do significant pruning.
There are many other ways to attach SPS corals to substrates.
Hot melt glue, fishing line, many other forms of epoxies and
any other things you can think of can be used to keep healthy
coral tissue immobilized and in contact with a suitable substrate.
If you have any questions
about this article, please visit my author forum
on Reef Central.