well, they filter the water in a snese, they use all the calcium to grow, and need to be feed phytoplankton, they do require some intense lighting, but all in all, its just cause they look so damn cool! i would worry about lighting and feedign primarily. if you have enough light to support one you should be fine, because older clams get the majority of their energy from the products of their zoozxanthellae in their mantle. younger clams need to be fed more often with phyto, and there are different species of clams that have different tolerances to lighting as well. t. maxima and t. crocea are probably the most demandign of light, while t. squamosa, t. derasa, and h. porcellanis, and h. hippopus do fine in a variety of lightign ranges. id definately read up on it if you are interested because they are beautiful creatures and it is sad when one of them dies on you!
good luck
jon
