Any FAC available on clam selection?

[pbs911]

I am thinking about adding a clam to my 80 gal this weekend. I have enough lighting - 2 400MH 10,000 and 2 VHO acintics. I've read than clams bigger than 3" rely less on feeding than the small ones. Are there any sites that have FAC on selection? I saw the sticky and it answers questions on feeding. I just want to know what clam to is a good, colorful starter.

Thanks in advance.