e) Nitrate
Nitrate has often been implicated as a causative agent for failure in 
reef aquariums. However, if the truth be known, there has never been 
any conclusive evidence for this. As mentioned above, nitrate levels 
of 40 ppm have been measured in aquaria with large stony coral 
growths. It would safe to say that maintaining a low level of nitrate 
is still desirable, but one need not become fanatical about it. Where 
nitrate could still pose a problem though, is in undesirable algae 
growth.

f) Phosphates
Phosphates can cause problems in marine aquaria, especially reef 
aquaria if they are allowed to build to levels above 0.2 ppm. 
Elevated phosphate levels will fuel unwanted algae growth and 
interfere with the calcification processes of corals and coralline 
algae. Phosphates are present in many forms in the aquarium, not all 
of which can be easily measured. The real trick with maintaining low 
phosphate levels is to minimize their input and maximize their 
removal. 

Minimizing input relates directly to the quality of the freshwater you 
are using for evaporative top-offs. This water should be as free of 
phosphate and nitrate as possible. If you are using this water to make 
kalkwasser then the high pH of this solution will result in the rapid 
precipitation of any remaining phosphate, in the form of calcium 
phosphate. Beware also of any additives and salt mixes that may 
contain unacceptable levels of phosphate. Avoid using any liquid food 
supplements that may contain phosphate and check your activated carbon 
to make sure it does not release phosphate (see Delbeek and Sprung, 
1994). 

To maximize the output of phosphate the use of adequate protein 
skimming is essential. Also the frequent (every 2-3 days) cleaning or 
replacing of the prefilter is a must. In aquariums with poor water 
flow, the regular removal of detritus from beneath and between the 
rocks should be a part of your monthly routine.

g) Trace Elements
The topic of trace elements has become quite popular again in the last 
few years. As a rule, very little is known about what elements corals 
require to grow and survive. At this point it is safe to say that 
strontium is a very important element in the growth of many calcareous 
organisms. Strontium supplements can now be purchased in almost any 
marine reef aquarium store. Iodide appears to be another important 
trace element for corals, clams and crustaceans. Again, potassium 
iodide and other iodide sources are readily available for purchase. At 
the time of this writing, there is no substantial evidence for the 
importance of any other elements. That is not to say that in the 
future the importance of others will not come to light, but for now, 
these two are the only ones I can definitely say in my experience, are 
necessary for optimum growth.

Coral Care
Although a series of books could be written on the care of individual 
coral species, space limits me to generalizations on the more common 
genera. See Wilkens (1990), Wilkens and Birkholz (1986), and Delbeek 
and Sprung (1994) for more detailed information on coral 
identification and care.

Octocorallia
Alcyonacea
Leather Corals
 

There are many different species of alcyonacea that fall under the 
category of "Leather" corals. Most belong to the genera 
Sarcophyton, Lobophytum and Sinularia. Generally 
speaking they do well in moderate to strong lighting, and require a 
good current with frequent strong bursts. No feeding is required. Be 
careful when placing them in the tank as some varieties of 
Sinularia can sting other corals badly. Sinularia spp. 
can be easily propagated by cutting off small sections with sharp 
scissors and fastening the cuttings to a rock with thread or elastics. 
Protect the cuttings from strong currents until they firmly attach 
then treat them as adult colonies. Sarcophyton and 
Lobophytum spp. are more difficult to propagate. Cuttings can 
be taken from the capitulum but this tends to leave the mother colony 
with a moth eaten appearance.

Colt Corals (Cladiella spp.)
These soft corals include the common Colt Coral as well as a number
of other varieties. They do quite well in medium to strong lighting
with a moderate current. No feeding required. Can be propagated by 
gradual pinching off of branch tips or by cutting with scissors.

Tree-like Alcyonacea
The other genera in this order tend to have a tree-like appearance 
such as Litophyton, Lemnalia and Capnella. These 
corals tend to be more delicate than the other alcyonacea and are not 
recommended for the beginner. They prefer medium to high light 
intensities and medium to weak water motion. Feeding is not required 
but they will take fine planktonic food when offered

Other Soft Corals
Another common soft coral is Anthelia spp. These have large 
polyps with long stalks (6 inches). They grow as an encrusting mat and 
require moderate to strong lighting and moderate current. Closely 
related to Anthelia is the genus Xenia. There are many 
species of Xenia available, some that rhythmically pulsate 
their polyps. Xenia tend to be rather delicate and are not 
recommended for the beginner. These two corals do not feed and most 
likely get their nutrition from the zooxanthellae and direct uptake 
from the water.

Gorgonacea
Photosynthetic Gorgonians
The majority of Caribbean gorgonians are photosynthetic and are
therefore easy to keep without direct feeding unlike their Pacific
cousins that are not photosynthetic. Most have brown, blue or purple
stems, some are yellow, and all have brown polyps. The thicker
branched varieties are the easiest to keep. Some forms will grow very
quickly (inches per month) while others grow more slowly. They can be
easily propagated through cuttings and can be given supplementary
feedings with live baby brine or adult brine shrimp. I have also fed
them successfully with live black worms. Not all species will feed and
it is not mandatory to feed photosynthetic gorgonians. Specimens
belonging to the genera Pseudoplexaura, Pterogorgia,
Pseudopterogorgia, Eunicea and Muricea are all
easily maintained. Gorgonians require moderate current with the
occasional strong burst and medium to strong lighting. Many
photosynthetic gorgonians are sensitive to ultraviolet light. If your 
specimens do not open after a period of time try placing a piece of 
U.V. absorbing material under your light source such as glass or 
Plexiglas; the recovery is often dramatic. If there are bare portions 
of the skeleton showing, these can regrow very quickly provided the 
specimen is healthy and no microalgae is growing on it. Sometimes 
there are numerous bare spots, especially at the tips, when a specimen 
first arrives from the collector. If you take a pair of scissors and 
cut these bare areas off, as close to the living tissue as possible, 
the ends will quickly (within a day) seal over and no algae can invade 
the colony.

Stolonifera
Star Polyps (family Clavulariidae) come in a variety of colours 
ranging from brown to iridescent green. They do well in medium to 
strong light and if given a strong current, will rapidly spread over 
rocks and glass. No feeding is required. These corals can be easily 
propagated by cutting off small pieces and placing them in other areas 
of the tank. If you have no substrate try placing some sections of 
star polyp on the bottom of the tank. They should spread out over the 
glass making a nice "lawn" of soft coral.

Red Pipe Organ coral (Tubipora musica) requires medium to strong 
lighting and medium to weak water movement. Feeding is not required 
and it is likely that they receive enough nutrition from their 
zooxanthellae and direct uptake from the water. Calcium, strontium, 
and perhaps iron, are the key elements to encourage this species to 
grow in the aquarium.

Hexacorallia
Corallimorpharia (Mushroom Anemones)
Various species are available in a variety of colours and forms. Some
forms do well in lower light areas of the tank (i.e. brown varieties)
while others require more light (blue varieties). In general, they
require gentle current flows, not strong and do not need to be fed.
Keep them away from stony corals as they tend to damage them quite
easily. See Delbeek (1987) for more detailed information on keeping
mushroom anemones.

Scleractinia
If, after 6-12 months, your tank is doing well and you have no
microalgae problems then you can try some stony (hard) corals. 
However, I hesitate to recommend them to beginners and you can have a 
very nice and interesting tank without them. If you can concentrate on 
soft corals you should have a very stable tank that will grow quite 
nicely. Eventually you can propagate many of the soft corals from 
cuttings and trade them for other species you may not have.

If you would like to try keeping some stony corals, the following is a
listing of the common stony corals offered for sale. First, however,
there are a few points you should make note of before you purchase a
specimen. Number one is to make sure that there are no bare areas on
the coral skeleton. These areas may recover but more often than not,
they only become substrate for microalgae. Once microalgae takes hold
you can pretty well say goodbye to that particular piece; eventually
the algae will spread and destroy the rest of the coral. It is
possible for such a piece to heal but this requires that no microalgae
be present in your tank and that none has begun to grow on the damaged
areas. Secondly, check to see that the tissue of the coral extends 
well over the edges and down the sides of the skeleton. This is not 
always easy to see, as the polyp(s) may be so large that they obscure 
the skeleton underneath e.g. Euphyllia and Catalaphyllia 
corals. Usually, if all other conditions are optimum (i.e. calcium 
levels are over 420 mg/L and adequate lighting) the coral should 
regrow these areas without too much difficulty. The exception is when 
microalgae has impregnated the skeleton already. Ask the salesperson 
to gently agitate the piece so that the polyp begins to retract, this 
will give you a good view of the skeleton and the associated tissue.

The easiest to keep stony corals are Plerogyra sinuosa (Bubble 
Coral), the Euphyllia spp. corals (i.e. Hammer Coral E. 
ancora and Octobubble Coral, E. divisa, are the two 
hardiest), Favia spp., Favites spp., Herpolitha, 
Polyphyllia, Fungia and Catalaphyllia (Elegans 
Coral). Several of the so-called open brain corals 
(Trachyphyllia) are quite hardy as are the Turbinaria 
(Chalice/Plate) corals and Cynarina corals (Meat Polyp). Most 
require only moderate lighting to do well, while Turbinaria 
does best under stronger lighting. They will also accept feedings of 
shrimp and clam but these should be kept to a minimum (e.g. once every 
two weeks to a month), if at all. For stony corals to do well you 
should maintain a calcium ion level of at least 420 mg/L, there should 
be NO microalgae present in the aquarium and a strontium solution 
should be added weekly. These corals do well in gentle to medium 
currents. The Euphyllia and Catalaphyllia do enjoy the 
occasional strong burst of current. Plerogyra, Euphyllia 
and Catalaphyllia corals are capable of strongly stinging other 
corals. Make sure they are placed far enough away from other corals 
such that their long "sweeper" tentacles can not touch them.

Some stony corals have been observed to release eggs and sperm in the 
aquarium but no reports have been seen on the success of planula 
formation. However, asexual reproduction has been observed in many of 
the genera listed above. Asexual reproduction strategies in corals 
include asexually produced brooded planulae, the formation of polyp 
"balls", polyp "bail-out", fission and fragmentation, outgrowths and 
various means of "budding" (Delbeek and Sprung, 1994).

A technique employed by faviid corals is the formation of a single 
polyp with a bit of skeletal material which, when heavy enough, 
separates from the parent colony and settles on the adjacent 
substrate. Furthermore, large single-polyped corals such as 
Trachyphyllia, Euphyllia and Catalaphyllia, may 
produce unattached septae that may drag a bit of tissue with them as 
they separate from the parent by their weight, forming a new colony 
(Delbeek and Sprung, 1994).

Environmental stress plays a role in the stimulation of other means of 
asexual reproduction. In the case of polyp "bail-out" water 
temperature, oxygen concentration, pollution, or other environmental  
stimuli cause a polyp to separate from its skeleton and drift free. 
This affords great opportunity for dispersal away from the site of 
stress, without formation of planula larvae.

In aquaria, polyp separation from the skeleton can occur slowly as a 
result of numerous circumstances. This polyp separation is quite 
distinct from the bail-out method that occurs in nature. It is much 
slower, and is more akin to slow death than a quick escape. Such 
separation can be healed if caught in time, and it is also possible 
for a separated polyp to form a new skeleton. Portions separated may 
form new skeleton and drop off as a new colony as in 
Catalaphyllia (see Delbeek and Sprung, 1994).

The other environmentally induced means of asexual reproduction is the 
formation of anthocauli in fungiid corals. The environmental stressor 
is typically an injury to the original polyp, such as burial, stinging 
by an adjacent anemone or coral, or predation by fish or 
invertebrates. The area of tissue loss soon produces tiny individual 
polyps called anthocauli. These form a skeleton of their own as the 
grow, and eventually they separate from the original, injured fungiid, 
forming a complete new coral. The small point of attachment, once 
broken, forms a new anthocaulus on the original Fungia, so the 
reproduction is perpetual. Hobbyists have used such injured, 
reproductive Fungia and Herpolitha specimens to 
propagate new colonies for sale and trade.

Finally, Euphyllia, Catalaphyllia and 
Trachyphyllia species may also produce new polyps like 
anthocauli between the septae when injured, and Euphyllia spp. 
regularly bud new polyps along the walls of the skeleton when they are 
healthy. These new polyps break off at the constricted point of 
attachment when they are large enough, or fuse with the main colony to 
form a new branch (Delbeek and Sprung, 1994).

Zoanthidae
Zoanthids (Button Polyps) are generally very easy to keep and 
propagate, and they come in numerous colours and shapes. They form 
colonies on live rock and spread as an encrusting growth. Requirements 
include moderate to strong light and medium to strong water motion. 
Some genera such as Palythoa spp. will feed. Parazoanthus 
gracilis is a species that is commonly available to hobbyists. 
These colonies are usually bright yellow but in the aquarium they tend 
to darken to a yellowish-brown colour due to the increase of 
zooxanthellae pigments. Some of the larger tentacled species (i.e. 
Palythoa and Parazoanthus) will feed on adult brine 
shrimp and black worms, but if fish are present in the aquarium enough 
stray food particles should reach the zoanthids.

Keeping corals in captivity is not as difficult task as many would 
have you believe but it is not without its own problems. Sudden 
changes in water quality, sudden outbreaks of undesirable algae and 
other unexpected maladies can tax the patience and resolve of even the 
most experienced hobbyists. However, the potential rewards and 
satisfaction that can be gained from a thriving captive reef ecosystem 
is a powerful lure for many aquarists. 


Suggested Readings
Alderslade, P.N., Lovell, E.R. and C.C. Wallace. 1984. Corals. In: 
Reader's Digest Book of the Great Barrier Reef. Mead and 
Beckett Publ., Sydney, Australia.

Barnes, R.D. 1974. Invertebrate Zoology. W.B. Saunders Co., 
Toronto.

Delbeek, J.C. 1989. Reef Aquariums Part 1: An Introduction. Aquarium
Fish Magazine 2(2):24-33.

------------- 1990a. Reef Aquariums Part 2: Filtration . Aquarium Fish
Magazine 2(3):28-37.

------------- 1990b. Reef Aquariums Part 3: Chemical Filtration.
Aquarium Fish Magazine 2(4):16-28.

------------- 1990c. Reef Aquariums Part 4: Lighting . Aquarium Fish
Magazine 2(5):26-37.

------------- 1990d. Reef Aquariums Part 5: Nutrition . Aquarium Fish
Magazine 2(6):26-35.

------------- 1990e. Reef Aquariums Part 6: Coral Aggression. Aquarium
Fish Magazine 2(7):26-32.

------------- 1990f. Reef Aquariums Part 7: Examples of the best.
Aquarium Fish Magazine 2(8):20-31.

------------- 1990g. Reef Aquariums Part 8: More Representative Reef
Systems. Aquarium Fish Magazine 2(9):20-31.

------------- 1993a Your first reef aquarium: Stocking for succcess.
Aquarium Fish Magazine 5(9):18-31.

------------- 1993b. Your first reef aquarium: How to create a
miniature coral reef system at home. Aquarium USA 1994: 18-32, 114-
122.

------------- and J. Sprung. 1994. Reef Aquarium: A Comprehensive 
Guide to the Care and Maintenance of Tropical Marine Invertebrates. 
Stony Corals and Tridacnid Clams. Ricordea Publishing, Coconut 
Grove, FL, USA, 33133. 544 pgs.

Faulkner, D.J. 1992. Biomedical uses for natural marine chemicals. 
Oceanus 35:29-35.

Fautin, D.G. and G.R. Allen. 1992. Field Guide to Anemonefishes 
and their Host Sea Anemones. Western Australia Museum, Francis St., 
Perth, WA 6000.

Hyman, L.H. 1940. The Invertebrates: Protozoa through 
Ctenophora. McGraw-Hill Book Co. Inc., New York, London, 726 pp.

Kaplan, E.H. 1982. A Field Guide to Coral Reefs of the Caribbean 
and Florida. Houghton Mifflin Co., Boston, 289.

Veron, J.E.N. 1986. Corals of Australia and the Indo-Pacific. 
Angus and Robertson, Publ., North Ryde, Australia, 644 pp.

Vine, P. 1986. Red Sea Invertebrates. IMMEL Publishing, London, 
England, 224 pp.

Wilkens, P. 1973. The Saltwater Aquarium for Tropical Marine
Invertebrates. Uppertal Elberfeld, 216 pp.

---------- 1975. An experimental marine aquarium. Mar. Aquarist 6(5):
49 - 55.

---------- 1976. More flower animals. Mar. Aquarist 7(10):31-44.

---------- 1990. Invertebrates: Stone and False Corals, Colonial
Anemones. Engelbert Pfriem Verlag, Wuppertal, Germany, 136 pp.

----------- and J. Birkholz. 1986. Invertebrates - Tube-, Soft- 
and Branching Corals. Engelbert Pfriem Verlag, Wuppertal, Germany, 
134 pp.

Williams, G.C. 1993. Coral Reef Octocorals: An Illustrated Guide 
to the Soft Corals, Sea Fans, and Sea Pens inhabiting the Corals Reefs 
of Northern Natal. Durban Natural Science Museum, 63 pp.

Wood, E.M. 1983. Reef Corals of the World: Biology and Field 
Guide. T.F.H. Publications, Inc., Ltd., Neptune, NJ, U.S.A. 256 pp.


SideBar

Common Soft Coral Genera            Soft Coral Common Name             
------------------------           -------------------------             
   Anthelia                  Waving Hand Coral    
   Capnella                  Kenyan Tree Coral
   Cladiella                 Colt Coral, Cauliflower Coral
   Clavularia                Waving Hand Coral
   Cornularia                Star Polyp  
   Dendronephthya            Tree Coral                         
   Heliopora                 Blue Coral
   Lemnalia                  Tree Coral, Lemnalia
   Litophyton                Tree Coral
   Lobophytum                Leather Coral, Devil's Finger
   Nephthea                  Tree Coral    
   Sarcophyton               Leather Coral
   Sinularia                 Finger Leather
   Tubipora                  Pipe Organ Coral
   Xenia                     Pulsating Polyps