Because this seems to come up time and time again here and because I had many questions that had contradicting answers about having a clam in a nano sized tank under less then metal halide lighting I did quite a bit of research on the subject and have consolidated it into a FAQ.   Clams   Scientific Information:   Phylum: Mollusca Class: Bivalvia Order: Veneroida Family: Tridacnidae Genus: Tridacna Species: Multiple. See below     Common Names: Crocea, Derasa, Gigas, Maxima, S