Laurie Smith AS, BSN, MSB
Who needs milk when one can have Tridacna clams??? After all, milk does absolutely nothing for the nitrate levels in your tank… though calcium does indeed do a clam good! Among my reefer buddies (Ahem, saltwater reefers), clams seem to have acquired a rather ominous reputation for being hard to keep. It is a common comment to hear someone say at an event that clams are such beautiful creatures… but alas, so hard to keep. While it is true that there are varying degrees of hardiness among clams, it is certainly NOT true that clams are harder to keep given a bit of forethought and research prior to purchase. In my humble opinion, it is less important how your tank is set up with equipment than it is being educated prior to purchase so that you can pick out the clam that best fits your tank environment. Light, flow, tank mates, disease ‘red flags’, and the type of clam itself that you buy can all dictate the survival expectation of that little clam in the pet store window!
In medicine, pain is often referred to as the ‘Fifth Vital Sign’… In reefing, I think light is often missed as a tank parameter itself. It is well known among reefers that certain corals like small polyp stony corals require light of a certain parameter and strength to keep. What I think happened to clams in the public mind set is that the light requirements of certain clams became generalized to be ‘common knowledge’ for the husbandry of all clams.
This can’t be farther from the truth because clams exist along a rather wide continuum regarding their needs for light. Derasa, squamosa, and gigas clams have the wonderful perk of being much less light needy and can be successfully kept in tanks 12-14 inches in depth or so under power compact lighting that is also capable of sustaining compatible coral life. T5 high output lights are also proving to be viable and less expensive options than metal halide for the successful husbandry of these beautiful creatures.
When choosing clams, also try to remember that crocea and maxima clams are more light needy than the other three types and will require placement higher in the tank. Clams also require more light in relation to the amount of color in their mantles. Using this as a guideline, an educated reefer will remember that the beautiful ultra or electric grade clams will place much higher light demands on your budget. Browning out of the mantle is an ominous sign that commonly is related to the age of the light bulbs being used in the tank or the type of light itself. In addition to this, look for rocky over hangs or coral growth that is shading the clam from the penetration of light into the water above the clam.
Clams are filter feeders, meaning that they require an appropriate amount of flow in order to strain water that passes through them for food. They remove calcium, nitrates, and often live food from the water. This makes them an awesome choice for biological export of stubborn nitrate levels, and also helps stabilize calcium and carbonate in your tank water.
Now, having said that clams enjoy a good amount of flow, I must also caution you that there is indeed such a thing as too much flow for a clam. Having the water whipping around the tank at light speed will indeed cause more water to pass through the clam, but it will irritate the clam’s mantle causing the clam to close up and thus affects the amount of light it can soak up. It also makes it much harder for the clam to feed physically as the water current takes the particles through the clam faster than it can strain. A similar thing happens to your kidneys with high blood pressure- the higher the pressure above 140 systolic, the higher the physical strain on your filters in the kidneys, and the less able your kidneys are to strain your blood of unwanted particles... Too little blood pressure, and the kidneys lose the ability to filter altogether. Lots of things in nature rely on appropriate flow in order to sustain life, and clams are certainly no exception. Although I must say that I would much rather blow out a clam than a kidney!!
Proper Tank Mates (Who Do Not Have The Munchies)
In general, I think that this category of clam husbandry is much more the common cause of death for a clam than disease or parameters are. I say that because the parameter requirements of clams are much the same as they are for other corals (76-82 degrees Fahrenheit, PH 8.2-8.4, salinity 1.022-25, and calcium levels of 400-450). However, there are many kinds of tank mates that will kill a clam by outright eating it or nipping the mantle so much that the clam dies from complications of irritation. Among the most well known are certain types of snails (Pyramidellid, etc), some types of angels, some types of wrasses, some types of butterflies, some types of worms, and legions of fish that were fine with the clams that were already in the tanks they were introduced to… but decided to make a meal of clams subsequently added. If I listed them all, Wet Web would wind up paying me for a 15 page article!!! My advice to you is to thoroughly research clam compatibility with the specific type of fish you plan to add after the clam… and to thoroughly research your fish currently in your tank before breaking down at your local fish store for that wicked cool ultra grade crocea. And even after that, keep a watchful eye on the heightened interest of some ‘clam safe’ fish. Fish have individual personalities like anything else, and can be trouble if their curiosity is piqued. I once saw a very comical picture of a garden variety yellow tang that had stuck its snout into a clam fairly deeply to check it out (Sniff it maybe? Who knows)… and wound up dying a nasal death because the clam snapped shut on the offender fearing predation and didn’t let it go for several days. I would not want to be the tank owner who had to make the decision to either accept to death of the tang, or pry the clam open and possibly killing it to set the tang free. L
Disease ‘Red Flags’
According to www.clamsdirect.com, pinched mantle is suspected to be caused by a protozoan that is currently being identified. The mantle curls upwards and in towards the clam and generally progresses to a more and more upset state until the clam eventually dies. To combat this, Barry Niegut recommends using a fresh water dip in RO water for 25 minutes. Gently shake the clam to get the RO water into all parts of the clam as it will closed up tighter than Scrooge at Christmas with the coal. While this is admittedly incredibly stressful for the clam, it causes the death of the causative organism and is the easiest and most well known curative readily available in your home.
Ok, did I mention that clams dislike air? Are you a reefer who enjoys dumping change water straight into the display tank? Or aims power heads at the clams in an attempt to get it to dislodge its byssal threads (or foot)? Power heads move water very well, but at times they also move bubbles. And dumping change water straight into the tank causes many problems… one of which is the aeration of the water as it enters the tank. This air can get caught in the clam’s mantle or worse, inside the clam itself causing sickness and potential demise of the clam.
Clams are nonverbal little guys who don’t have a great many ways to tell you exactly what is wrong with them. Your body many times is the same… for instance, how many biological problems start out with ‘flu like symptoms’ before progressing to some all out disease state? Gapping is a clam’s version of ‘flu like symptoms’. In layman’s terms, gapping is occurring when the intake filter hole of a clam (the larger hole you see in the fleshy center of the clam versus the intake siphon which is a smaller hole on a ‘stick’ above the filter hole) is much larger than normal and loses muscle tone- causing the actual edges of the hole to look slightly frilly. If you think this may be occurring in a clam at a retailer, ask them how long they have had the clam and do not buy it. Watch out for clams that are irritated or ill from the stress of being shipped and have no acclimated well to the retailer’s tank parameters. Also, keep in mind that you want a very happy and acclimated clam, as you are about to subject it to the stress of acclimating a second time to your tank… The worst possible thing you can do to a clam is take buy a clam trying to acclimate to a set of water parameters and immediately try to dunk it into your tank- a completely different water recipe.
Where Do I Put My Clam?
It is my hope that after reading this article, reefers of every ability level will find success with clams. Clams really are a wonderful addition to tanks, both biologically through nitrate export and aesthetically with their gorgeous patterns and colors. Very little matches the vibrancy of a clam, and they add wonderful depth and character to the saltwater tank.