I'm far from an expert on Clams, but I have the exact same setup(lighting and tank dim.) as you and am also considering a clam. I have been told that a Squamosa is the least light hungry and could probably survive high up in my tank. Feeding is of the upmost importance for these guys, especially when smaller(4" and under) And most of them get quite big. HTH Reeferaddict:bum: