3 or 4 Croceas (some Ultra Greens and Ultra Blues) up there would look awesome (but super expensive).
http://www.animalnetwork.com/fish2/a...ll/default.asp
"A unique protective mechanism
T. crocea has developed a very interesting way to protect itself from extremley strong water current and surge. Because it is found mainly in the shallow reef zone on brightly illuminated reef tops, it has developed a very strong byssal attachment (“foot”) — the strongest in all tridacnids — and has even learned to “bury” itself into solid limestone"
"Aquarium care
T. crocea has adapted to the upper portions of the reef and can stand quite strong and sudden changes in salinity or temperature compared with species from deeper reef habitats."
"Water motion and feeding
T. crocea can deal with strong water motion. Though it should not be constant, the strong water movement that is normally found in the upper portion of a reef tank near the surface does not adversely affect this species. Changes in temperature or pH also do not harm this clam as much as they do other species that come from deeper reef habitats with more stable water conditions. "