Derasa Clams

Undoubtedly, clams of the genus Tridacna (the so-called giant clams) are highly desired by marine, and especially reef, aquarium hobbyists. This is quite understandable as they are all interesting and attractive. That being said, some tridacnid species are notably easier to care for than others. And, to let it be known, none could rightly be described as “easy to care for.” Thus, for first-time tridacnid clam keepers, the best choice is the hardiest--T. derasa or the derasa clam. Derasa clams get pretty large at around a couple feet maximum length and are indeed the second-largest tridacnids; however, this species is nowhere near as bulky as the largest species, T. gigas (which is perhaps its closest relative). Derasa clams have a very distinctive color pattern over their large, fleshy mantles. While there are lots of variations, the species often bears yellowish blotches or squiggly lines over a darker golden brown background, occasionally with a bluish or greenish sheen. The mantle edges are often lined in bright blue or green. It oft-used common name, the smooth giant clam, comes from its shell, which lacks the huge scales and rough texture of most of its relatives. This feature helps to distinguish derasa clams from younger T. gigas. Derasa clams were at one time collected in huge numbers for food as well as for their ornamental shells or for aquarium use. This led to huge declines in natural populations. Thankfully, they are now raised on farms both for their flesh as well as for the aquarium trade. Captive bred specimens have proven to be considerably hardier and less delicate than wild stock. In this section, you will learn all about the biology derasa clams and how to properly care for one of your own.