At less than a third of the size of the true giant clam (Tridacna gigas), the small giant clam deserves its name. As an adult, it has a large shell that adheres to a rock. When open, the bright blue, green or brown mantle is exposed and hides the edges of the shell with its prominent and distinctively smooth round edges. The Tridacna maxima clam is a bivalve mollusk, referring to the two valves on the mantle.
These siphon water through the body to extract oxygen from the water using the gills, and to feed on algae. Clams are relatively hardy and well suited for the saltwater aquarium. One thing that must be kept in mind when adding a new specimen to an aquarium is that clams do not react well to being moved around. It is my recommendation that a good consideration of where you want to put your clam should be decided before placing it in your aquarium.
An excellent book available at amazon.com is Daniel Knop's "Giant Clams: A Comprehensive Guide to the Identification and Care of Tridacnid Clams". This book is the best source for information on the Tridacnid clams. The chapter on clam diseases is especially interesting, as is the information on keeping clams in the aquarium.
Daniel Knop is also the Editor and Contributing Photographer for the German magazine Koralle, Coral magazines counterpart. Coral puts out a fantastic publication on a bi-monthly basis. I subscribe to Coral magazine for my clients and they can look forward to receiving their next issue featuring Anemonefishes soon.