Clams have some simple basic requirements- BRIGHT light, adequate calcium (400ish), and alkalinity (7-10 dkh). Other than that, the typical reef aquarium parameters of salinity, temp, etc. are ideal. As rhomer stated, clams don't "need" to be fed. The can and do filter feed, but our aquariums typically will provide mopre than enough "natural" foods.
Some things to be concerned about environmentally (beyond what we discussed above)- inappropriate tankmates and some clam specific diseases. For example, fish or inverts that pester a clams mantle can easily kill the clam, and some pathogenic issues like pinched mantle disease can also kill a clam rather quickly. Be sure to do a lot of reading, clams are often very misunderstood.