A Brief Guide to the
Selection and Placement of Tridacnid Clams
By Barry Neigut
James Fatherree and Barry outside the latter's business, Clams Direct
you want to dress up your reef tank by adding a Tridacnid clam? If
you're like many reef hobbyists, the answer is a resounding "Yes!"
|Before you run out to buy
that prized Tridacnid clam, there are several things that you need to
of all, make sure that your aquarium has been established long enough to
support the needs of your new addition. A good indication of your aquarium’s
suitability for Tridacnids is a nice growth of coralline algae. Such growth
usually occurs 6 months to a year after your aquarium has been established.
sure that your fish and invertebrates are compatible with Tridacnids. Some
cleaner wrasses have proven to be destructive to clams, nibbling on their
mantles and otherwise preventing full expansion. Other fishes may also
harass clams. For example, I once had a Copperband Butterfly that was
introduced into an established aquarium that contained clams. It never
bothered the clams at all, until one day I placed a few new clams into the
aquarium and he attacked them within moments. Observation and careful
selection of fishes is critical if you tend to be successful with clams.
Another important consideration is proper
lighting. Some clams require intense lighting to maintain their long term
health and color. Such lighting is most effectively and economically
provided by metal halide lamps. The wattage and number of lamps required
depends upon the dimensions of your system and the species that you intend
to keep. Suffice it to say, in most aquariums with a depth of 20" to 30", a
175 - 250 watt metal halide lamp per square foot will do a great job. In
aquariums less than 20” deep, you could also utilize compact fluorescent
(PC) and VHO bulbs. Keep in mind that the different species will dictate
the lighting requirements. For example, Tridacna crocea and Tridacna maxima
require more intense lighting than the other species. Smaller Tridacnids,
and those with brown mantles do not require as much light as those with
temperatures of 6,500K-10,000K are ideal, and will provide the spectrum the
clams need for growth, and will help maintain optimum coloration in the
New Growth Visible at the
Along with proper lighting, water chemistry plays
an important role in health of Tridacnids. The water chemistry should be
stable, with no large swings in your specific gravity or pH.
are some recommended environmental parameters:
Calcium and alkalinity (carbonate hardness) are the building blocks of
Tridacnid shells and should be measured on a regular basis and maintained at
the levels listed above. The growth of a juvenile clam is readily evident on
the upper margin of the shell, and is a good indicator of the health of the
clam. Poor growth of clams is a good indication that something is wrong in
the system, and in most cases caused by a lack of available calcium or
Calcium is not the only element that is needed by clams for proper growth.
Some hobbyists choose to add iodine supplement to their clam tanks because
the believe that iodine helps detoxify excessive oxygen radicals produced by
symbiotic algae. If you plan on supplementing iodine, be sure to test the
water on a regular basis to avoid overdosing which may lead to nuisance
algae and other potential problems within the aquarium. Many aquarists
believe that enough iodine is added inadvertently through feeding and water
changes since iodine is present in both good quality salt mix and in most
other trace elements are important to clam health, but trace element
solutions are easily overdosed. Most trace elements can be safely and easily
maintained through regular partial water changes. I strongly believe that
doing small water changes on a frequent basis is better than larger water
changes on a less frequent basis since trace elements will be added more
often. Partial water changes have the added benefit of reducing pollutants.
Some beautiful specimens
of Tridacna maxima
that you’ve created the right environment, it’s time to choose that
beautiful specimen for your aquarium. Let's take a look at some of the ways
to be sure you are getting a healthy and attractive specimen.
examining Tridacnids, make sure that the mantle extends well over the shell.
Also, the clam should show a healthy response behavior to stimuli. This is
done by placing your hand between the light source and the clam. This should
cause the clam to close quickly and re-open after a few moments.
generally appear more attractive when viewed from the top than they do when
viewed from the front of the aquarium. Many times, the colors will brighten
when you place them under more intense lighting, and could fade under
inadequate lighting. Do keep this in mind when evaluating a prospective
Tridacnid for purchase.
to see if there is any “bleaching” or white areas on the mantle. This
normally appears between the incurrent and excurrent siphon. Sometimes,
this bleaching will appear brown or “washed out” in color, but don’t mistake
a gold color as bleaching. The gold clam pictured above is not bleached.
Inspect the clam around the mantle and “byssus” (foot) to make sure there
are no Pyramidellid (“Pyram”) snails. These parasitic snails can do serious
damage to the clam and must not be allowed into your aquarium. Make sure
that you carefully examine the specimen for the presence of jelly-like sacks
which house the eggs of these snails. Several dozen snails can hatch
simultaneously. If Pyramidellids are discovered in your aquarium, there are
a few fish that will help in controlling them, such as Coris formosa,
Coris gaimard, and the popular Sixline Wrasse,
Pseudocheilinus hexataenia. Manually removing these pests at night (when
they are feeding) may also be necessary.
for “gaping,” a condition in which the animal’s shell is completely
open, the mantle poorly extended, and the incurrent siphon appears to be
stretched. In most cases, this is caused by some form of stress. This is
often caused by shipping, and in most cases will cease after a few days.
Having kept and shipped thousands of clams, I have noticed that Tridacna
crocea displays this condition more commonly than other Tridacnids.
However, Tridacna crocea
seems to recover from the condition whereas it is cause for concern in
the shell to make sure it is not broken, and that the mantle is not torn or
ripped. Do not purchase an animal that displays any signs of damage.
to purchasing your clam, ask if the specimen was collected in the wild or if
it was cultured. Usually cultured clams are easier to keep and maintain.
One of the potential problems with wild-collected clams is the collection
process itself. Improper collection techniques can result in serious damage
to the clam, particularly the byssal gland. Carefully inspect your
prospective purchase to assure that the byssal tissue is not torn or hanging
from the specimen. This damaged tissue can result in the development of a
bacterial infection that caused the clam to die.
all possible, find out how long the clam has been in the dealer’s inventory.
Ask your dealer if you can purchase it and leave it in his/her tank for a
few days longer. This extra time will allow you to observe the clam and make
sure that no infections or other maladies manifest themselves before you
take the animal home.
you bring your clam home, you will need to acclimate it to your water
conditions before placing it in your aquarium. This should be done slowly so
as not to stress the clam. New aquarium water should be added to the bag or
container holding the clam a small amount at a time until the water volume
has doubled. This process should take at least an hour.
must also be acclimated to new lighting. Place the animal in a dark tank and
let it acclimate to your lighting regime. You can then gradually increase
your lighting time over the course of a few days until you reach your
desired exposure time. Keep the clam facing upward toward the light so that
the full mantle is exposed to the light source. We do not want part of the
mantle to become bleached or lose zooxanthellae.
recommend that newly introduced clams be placed at the bottom of the tank
for about a week while deciding where to place it permanently. This will
also give the animal time to adjust to both your water and your lighting.
Tridacna derasa, Tridacna squamosa, and Tridacna gigas are best
placed on sandy substrate, whereas
Tridacna crocea and Tridacna maxima should be placed in the rock
work. Take notice of the currents in your aquarium, because most Tridacnid
clams do not like strong water movement. Tridacna maxima and Tridacnid
crocea can tolerate relatively stronger currents.
Another concern when placing Tridacnids is to consider what other animals
are in close proximity to your chosen location. You don’t want to put the
clam where it can be stung by any extended sweeper tentacles from resident
colors aren't required to make a clam beautiful, sometimes an amazing
pattern will catch your eye!
your ideal location for your Tridacnid is going to be on the substrate, I
would suggest that you place a small piece of rock or tile about 1/8” to
1/2” below the substrate. When the clam starts to lay down its byssal
filaments, it can attach to that object. This will also prevent potential
predators from entering the byssal opening and doing damage to vital organs.
Remember that acclimation takes time. When we transfer clams to a new
aquarium, environmental factors may be significantly different from those to
which the clams were previously accustomed. Thus, the clams must adjust to
the new environment. That being said, it is best not to introduce
more animals or change buffers (products) during this acclimation period. I
firmly believe that the less additives that we put into our aquarium, the
better the animals will be.
Well, there you have it--a quick summary of the
basics of selecting and placing Tridacnid clams in your aquarium. I hope
that this brief treatment has answered some of your questions regarding
these remarkable animals. I encourage you to educate yourself more with the
many resources available in print and on the internet. Never forget
that your clam is an incredible living animal. Choosing your specimen
carefully and providing for its well-being and health will bring you years
of viewing pleasure.
are welcome to check out my Clam Support Forum with any questions that you
might have on the selection, placement, and care of Tridacnids at