View Full Version : The Tridacnids

02-13-2009, 02:53 PM
The Tridacnids clams are the most readily available clams in the aquarium hobby. There are 5 species available to the hobbyist: Tridacna gigas, T. maxima, T. crocea, T. squamosa, and T. derasa. Tridacnid clams are not extremely difficult to care for, and all are zooxanthalic species. While these clams do derive nutrients from the zooxanthalae, when they are less than four inches they need copious amounts of food fed to them. Young Tridacnids rely heavily on feeding to grow to an adult size. Since they are filter feeders they will benefit greatly from phytoplankton and zooplankton feedings as well as offerings of Cyclopeze. Once they reach adulthood, the direct feedings do not need to occur as frequently as a much larger portion of their nutrition will come from the zooxanthalae. While T. squamosa and T. derasa do not require as much lighting as their three other cousins, they should still have a minimum of T5 lighting as their source. T. gigas, T. maxima, and T. crocea will survive under T5 lighting but they will require more watts then the other two; metal halides are really a much better choice as a light source for these three members of the genus.

Size must also be a consideration when purchasing one of these creatures. T. crocea is the smallest of the Tridacnids at just over six inches in length at full size and is thus one of the more popular choices in the aquarium hobby, second only to its cousin T. maxima. T. derasa, T. squamosa, and T. maxima all have a maximum size of about sixteen inches with T. derasa reaching upwards of eighteen inches. The monster of the genus has to be T. gigas; these are the “Giant Clams” of marine lore. Growing to over four feet in length and obtaining a shell weight of roughly five hundred pounds, these animals are truly the giants of the clam world. While they are available to the hobbyist, T. gigas will easily outgrow almost every home aquarium and should be left in the ocean and large commercial aquariums where they can be give the proper space to grow.

These species will all thrive in the home aquarium under the proper conditions and make wonderful additions to a display. The wonderful thing about a species such as T. maxima is that no two specimens are exactly alike and thus multiple specimens being kept in a tank can provide a wonderful variety of color and pattern to a display. Unless the hobbyist is willing to provide copious amounts of food to these creatures, they should not be purchased while still fewer than four inches in length.

If you are planning to keep a clam in your tank there are some species that should be avoided due to potential damage to the mantle. Hawkfish generally are not a great choice as tank mates due to their perching behavior. Hawkfish will perch on the top of the clam thus providing a stimulus for the mantel causing the clam to close and as a result they will not be able to eat or receive sufficient light for the zooxanthalae. The Coris wrasses should be avoided with clams as they will pick at and eat the mantles of the clams. Angels of the Centropyge genus will on occasion cause problems for Tridacnids; however this is as common as them causing problems for Long-Polyp Stony and soft corals. All of the larger angels of the Pomacanthus and Holocanthus genera are completely unsuitable as tank mates.

Parasites will often be the cause of clam deaths as well. Pyramidellid snails and commensal flatworms are a real problem for the Tridacnids in the home aquarium. In the wild they can cope with a few because they do not reach epic proportions on the each specimen due to being able to spread out, however in a concentrated environment like and aquarium these parasites become a real problem capable of killing the clam. Sixline Wrasses – Pseudocheilinus hexataenia are wonderful for controlling these two parasites while not harming the clam itself.

02-14-2009, 12:36 AM
thats a good write up. Thanks.