From FrugalReef

• Scientific Name: Tridacna Maxima
• Common Types Available: Comes in many colors of blue, green, gray, brown, purple or yellow
• Disposition: Completely non-aggressive

• Hardiness: Moderately hardy given strong lighting with low to moderate water flow
• Temperature: 75-84°F.
• Reef Safe: Yes
• Maximum Size: 14"

[edit] Feeding

Clams are primarily photosynthetic, but occasional feeding with phytoplankton inserted near the clam with a turkey baster up to twice a week is recommended. The younger the clam the more it benefits from frequent feeding of phytoplankton. High calcium levels (350-500 milligrams per liter) and good alkalinity in the aquarium are also required.

[edit] Tank Placement

Clams should be placed in the substrate at the bottom of the aquarium. They can be placed on rock, but will probably become attached to the rock and remain permanently affixed to it. Once a Maxima is attached they cannot be removed without killing them.

One recommendation for dealing with this fact is to place a small rock, approximately the size of the clam, just underneath the substrate where you will sit the clam. It will burrow down to this rock and attach. The clam can then be moved at will. This also protects the clams soft byssus openings from predators.

This clam prefers low to moderate water current

[edit] Lighting

Lighting is very important for clams. Clams that are on the brown end of the spectrum are acclimatized to high kelvin lighting. Clams that are blue are acclimatised to low kelvin lighting. Regardless of coloration, fairly intense lighting is required, with browns requiring less than blues.